U.S. marshals began on Thursday the seizure of the luxury $7 million Manhattan apartment of imprisoned fraudster Bernard Madoff and his wife, Ruth Madoff, officials said.

Two spokesmen with the U.S. Marshals Service in New York said marshals were carrying out the orders of a judge made in the days before Madoff was sentenced on Monday to an effective life term for his multibillion-dollar fraud.

The Madoffs agreed with U.S. prosecutors to forfeit any claims to their assets, property and accounts and after Madoff, 71, pleaded guilty in March to orchestrating Wall Street's biggest investment fraud.

There are marshals on the premises today, said spokesman Roland Ubaldo.

Another spokesman, Bill Dundon, confirmed it was the start of the process of taking over the apartment and its contents on Manhattan's tony Upper East Side.

Under an agreement with prosecutors made public Friday night, Ruth Madoff, 68, agreed to forfeit any claims to $80 million in assets and was left with $2.5 million in cash. The deal includes the couple's $7 million Manhattan apartment; an $11 million house in Palm Beach, Florida; and a $3 million residence on New York's Long Island.

The deal does not rule out future criminal charges or civil charges by regulators.

U.S. District Judge Denny Chin handed Bernard Madoff, 71, a sentence of 150 years imprisonment on Monday. He was also ordered to forfeit claims to $170 billion, the amount U.S. prosecutors said flowed through the principal Madoff account over the decades.

The figure is symbolic because he is not believed to possess anywhere near that much in money or assets.

(Reporting by Grant McCool, editing by Gerald E. McCormick)