Britain on Sunday froze the U.K.-based assets of Libyan ruler Moammar Gadhafi, members of his family and their representatives in accordance with U.N. sanctions imposed on Libya.

Those affected include Gadhafi's four sons and one daughter, the Foreign Office said.

"I decided to implement this UN resolution in the U.K. as quickly as possible, before the financial markets reopened," Treasury chief George Osborne said. "This is a strong message for the Libyan regime that violence against its own people is not acceptable."

No immediate figure was put on the value of the assets, which banks and other financial institutions are now under an obligation to track down and freeze. Cash, shares, bonds and property are among the items affected.

The Times newspaper reported this weekend that Gadhafi deposited 3 billion pounds ($4.8 billion) with a London private wealth manager last week, and held some commercial property and a 10-million-pound ($16 million) mansion in London. The report did not cite sources.

The U.K. also banned the unlicensed export of any uncirculated Libyan banknotes from Britain. All existing export licenses for goods and technology that could be used for internal repression have been revoked and future licenses will be subject to the U.N. embargo.

President Barack Obama said Friday the U.S. was freezing the assets of the Gadhafi regime, and Switzerland has imposed similar measures.

It was also unclear what Gadhafi-linked funds were still in Swiss banks. Libya withdrew almost $6 billion from Swiss banks in 2008 after the two countries became embroiled in a spat over the arrest of Gadhafi's son Hannibal in a Geneva hotel.

The withdrawal of the funds illustrates the blurred lines between Gadhafi's personal assets and those belonging to the Libyan state.

Libya's sovereign wealth fund is worth about $70 billion thanks to the country's oil and gas wealth. But much of that money is controlled by Gadhafi and his family, who are believed to have investments throughout Europe, including in Italy, Britain and the Netherlands.

Earlier Sunday, Britain revoked the diplomatic immunity of Gadhafi and his family and called on the autocratic leader to step down.

Foreign Secretary William Hague also said former Prime Minister Tony Blair has spoken to Gadhafi in the past few days, but did not disclose what was discussed. Hague defended Blair's friendly relations with Gadhafi's regime in the past and British trade dealings with the Libyan ruler.

He dismissed suggestions that Britain was complicit in the repression in Libya by selling it arms and trading in oil, and said it was right for Blair's government to establish commercial relations with Libya.

"It was right to be able to establish a relation ... that took Libya away from pursuing weapons of mass destruction programs and the state sponsorship of international terrorism," Hague told the BBC in an interview. "If we hadn't done, that we might be in a worse situation now."