London (CNN) -- Julian Assange will be arrested if he leaves the Ecuadorian Embassy in London, a Metropolitan Police representative said after meetings at the mission on Thursday.
The police official did not say if he met with Assange himself at the mission and did not give his name.
The announcement raises the stakes as the clock ticks down on the WikiLeaks founder, who wants asylum in the South American country.
Ecuador will make a decision within 24 hours on his asylum application, a diplomatic official said early Thursday.
Assange is seeking to avoid extradition to Sweden over allegations of rape and other sex crimes.
He has been arrested in absentia, said Britta Von Schoultz, a spokeswoman for the Swedish prosecutor's office.
His sister arrived Thursday afternoon to visit him for the second day in a row, but did not speak as she went into the diplomatic mission.
"We still can't make a final decision public yet until tomorrow," Ecuador's deputy foreign minister, Marco Albuja, told Australia's ABC News early Thursday. "The national government is considering its position and the president will give us his instructions tomorrow."
An embassy official told CNN Thursday that they're waiting for a decision to be made by their government but didn't know when that would come.
Assange remains at the embassy and is doing well, according to spokeswoman Priscilla Kohn.
"He's working, and spending a lot of time on the computer, as he usually does as part of his work," WikiLeaks spokesman Kristinn Hrafnsson told reporters.
Assange is subject to arrest for breaking the terms of his bail, London's Metropolitan Police said Wednesday, after he attempted to claim asylum.
He was arrested in Britain in 2010 because Swedish authorities want to question him about allegations of rape and sexual molestation. His bail conditions included staying every night at the home of a supporter outside of London.
"He is now subject to arrest under the Bail Act for breach of these conditions," police said Wednesday morning. But it is not clear that they will be able to arrest him, since diplomatic protocol prevents authorities from entering foreign embassies.
Britain's Foreign and Commonwealth Office said Wednesday that its officials "have met with the Ecuadorian authorities to discuss this situation," but released no details.
Assange sought refuge on Tuesday, five days after the Supreme Court of the United Kingdom dismissed a bid to reopen his appeal of the decision to send him to Sweden -- his last option in British courts. Assange supporter Gavin McFayden, who visited the WikiLeaks founder Wednesday, said he "seems in very good spirits."
"He seemed very grateful for the hospitality of the embassy," said McFayden, director of the Center for Investigative Journalism at London's City University. He said Assange is staying in a small room with a television, which McFayden called "not a luxurious accommodation." But he added, "We've all had worse than that."
"They're talking with the lawyers now about what they want to do," he said.
Two women have accused Assange of sexually assaulting them during an August 2010 visit to Sweden in connection with a WikiLeaks release of internal U.S. military documents. He was arrested in Britain that December and has been fighting extradition ever since, arguing the allegations are retribution for his organization's disclosure of American secrets.
Claes Borgström, the Swedish lawyer who represents the women, said the past year and a half "has been very frustrating and a difficult time" for them.
"The frustration for the clients is that they have been waiting for so long already, almost two years now," Borgström told CNN. "And after the decision from the Supreme Court, they were convinced that Assange would be coming to Sweden." Now that he has sought asylum in Ecuador, "You don't know how long it will take."
Assange's only further legal recourse would be to apply immediately to the European Court of Human Rights, and his attorneys have vowed to do so. He has said he fears that if he is extradited to Sweden, authorities there could hand him over to the United States, where he then could be prosecuted for his role in the leaking of classified documents.
Assange has not been charged with a crime, but Swedish prosecutors want to question him about allegations of "unlawful coercion and sexual misconduct including rape," according to a Supreme Court document. Ecuador said its decision to consider Assange's asylum request "should in no way be interpreted as the government of Ecuador interfering in the judicial processes of either the United Kingdom or Sweden."
WikiLeaks, which facilitates the anonymous leaking of secret information, has published some 250,000 confidential U.S. diplomatic cables, causing embarrassment to the government and others. It also has published hundreds of thousands of classified U.S. documents relating to the conflicts in Iraq and Afghanistan.
Recently, the organization has come under financial pressure, leading Assange to announce that WikiLeaks was temporarily stopping publication to focus on raising money. An announcement at the top of WikiLeaks' home page reads: "We are forced to put all our efforts into raising funds to ensure our economic survival."
During his wait for the Supreme Court to rule on his extradition, Assange has hosted a talk show on Russian TV. "The World Tomorrow" appears on the Kremlin-funded, pro-Russian network Russia Today. He hosted it from the Suffolk, England, mansion where he had been under house arrest with an electronic bracelet monitoring his movements.
He has interviewed controversial figures at odds with the U.S. government, including Hassan Nasrallah, the leader of Hezbollah, which the United States considers a terrorist organization, and Ecuador's president, Rafael Correa, who railed against the United States in his interview with Assange.
In 2010, a statement from Ecuador's foreign ministry appeared to offer the controversial Assange an invitation to discuss a trove of leaked documents. The ministry also offered to process a request for residency, if Assange chose. But a later statement from the Ecuadorian Embassy in the United States said that was not the case.
"While there was some confusion in the media flowing out of Quito yesterday, Ecuador's President Rafael Correa has clarified that his country has not invited WikiLeaks' founder Julian Assange to Ecuador," the statement read.
In Ecuador, Correa said at the time that his country had not made a formal invitation to Assange and that the ministry declaration, made by Deputy Foreign Minister Kintto Lucas, was "spontaneous" and personal in nature.
CNN's Stephanie Halasz in London and CNN en Español's Bertha Ramos-Rodriguez contributed to this report.