The Liverpool manager is determined to sign Heinze despite the stance of Sir Alex Ferguson, who is adamant the player will not be allowed to move to Anfield despite the Merseyside club matching United's £6.8 million valuation of the 29-year-old.

The stand-off is already in the hands of lawyers and could end up in court if United refuse to do business with Liverpool despite the get-out clause in the player's re-negotiated contract.

Benitez claimed a document that confirmed the Argentina defender's availability and that had been signed by a United official had been widely circulated.

"A lot of clubs, in many different countries, knew what the situation was," said Benitez after his side's 3-1 victory over South China in the Barclays Asia Trophy in Hong Kong. "I don't know what the problem is. We made an offer, they rejected it. I know what they're saying to the press but everyone in the world knows they signed a document."

Benitez believes that United have been caught out by their failure to place restrictions on the player's terms of release, though there is no guarantee Heinze and his representatives would have agreed to a clause preventing a future move to Liverpool or any other Premiership team.

He also believes Ferguson's questioning of the role played by Heinze's agents in the affair is a smokescreen designed to deflect attention from the club's oversight.

Heinze, who has yet to return to training after the Copa America, has two years left on his contract and it would appear that his future is likely to rest on whether he is prepared to take United to court to press for his release.

The furore overshadowed Liverpool's comfortable victory in the Hong Kong Stadium which came after first-half goals from John Arne Riise and Xabi Alonso and a 72nd-minute effort by Daniel Agger.

Fernando Torres and Ryan Babel had to watch from the stands after they failed to receive international clearance in time to play.

"Hopefully, we can sort something out for Friday so they can both play," Benitez said ahead of the final against Portsmouth, who beat Fulham 1-0 in the other semi-final. "I don't exactly know what the problem is but we need to find a solution."

In the absence of Babel and Torres, Benitez was delighted with the performance of one of his lower-profile summer signings, Andrei Voronin.

The Ukraine forward, signed on a free transfer from Bayer Leverkusen, played his first 90 minutes for the club and won the 26th-minute penalty that was converted by Alonso to double Liverpool's lead after Riise had scored from a 12th-minute free-kick. "Voronin has started well for us," Benitez said.

Less satisfying was the manner in which Benitez's side conceded a goal in the 32nd minute, with Scott Carson allowing a hopeful 40-yard free-kick to curl beyond his dive and into the top corner.

"Their goal was strange," Benitez said. "It was a surprise, and I'm sure he'll be disappointed with that. As a keeper, when you concede any goal, you're disappointed, but particularly when it's that kind of goal."