A fee of around 29.3 million pounds is thought to be on the table to bring the Argentina international to Old Trafford, with manager Sir Alex Ferguson desperate to improve his midfield.

Gaitan, 23, only signed for the Liga Sagres runners-up last season but has made a big impact and tops the Champions League assists chart this term.

Jose Irribaran, the player's official agent, said there had been informal talks between United and Benfica.

"I have not received any contact from United, but there have been conversations between the clubs," he told Antena.

"If these talks progress, then we will get our time to speak."

"But Nico is very happy at Benfica and is looking forward to enjoying a successful season."