James Gandolfini won a Screen Actors Guild award

Gandolfini, who plays mafia boss Tony Soprano, has lodged his own lawsuit which contends he should not be bound to his contract to film a fifth series.

He said he was not informed in time that Sopranos creator David Chase had signed up for another series.

But HBO's lawyer Bert Fields said the channel is now counter-suing to ensure Gandolfini turns up for the first day of filming.

"We are exposing the frivolous nature of (Gandolfini's) claims in our answer and cross-complaint," he said.

"If he doesn't show up by March 24, he's going to owe a huge amount of money."

Gandolfini said his contract stipulates he was to be informed of a new series being commissioned within 10 days.

'Train wreck'

But his lawsuit said an article in the Wall Street Journal newspaper in 2001 reported that a fifth series had been agreed, which he did not know about.

Mr Field said Gandolfini was notified in time and that the article is irrelevant.

The actor also said the contract exceeds the Californian legal seven-year limit for personal services.

"It looks like we're heading for a train wreck here," added Mr Fields.

The Sopranos recently picked up awards handed out by the Screen Actors Guild, with Gandolfini winning best actor in a drama series and co-star Edie Falco picking up best actress.

David Chase has said he will bow out after the fifth series, but HBO are still said to be trying to change his mind.