Radamel Falcao
Falcao joins United on a season-long loan deal. Getty

Monaco vice-president Vadim Vasilyev has revealed the club had little choice but to allow Radamel Falcao to leave after he told them he wished to join Manchester United.

The Premier League club sealed a sensational deadline day move for the Colombian international on Monday, bringing him to Old Trafford on a season long loan with the option to make the move permanent next summer.

Falcao only joined the Ligue 1 club last summer from Atletico Madrid but Vasilyev has stressed to supporters once United made their interest known they had no choice but to negotiate.

"I'm sorry for our supporters because of the departure of Radamel Falcao," Vasilyev is quoted as saying by L'Equipe.

"We felt once the player had expressed his desire to join Manchester United, it was inconsistent to block the move."

Falcao's departure is the second blow Monaco have suffered in their attempts to challenge Paris Saint Germain at the summit of French football following the departure of James Rodriguez but Vasilyev insists the ambitious project at the principality will continue.

"Our project does not end here and we will continue to progress and give everything to make the best season. I wish the best to Radamel at Manchester United but I am sure we will have some results this season."

Falcao was officially unveiled as United's sixth signing of the summer early on Tuesday morning following the closure of the transfer window. The Colombian international has been awarded the number nine shirt.

"I am delighted to be joining Manchester United on loan this season. Manchester United is the biggest club in the world and is clearly determined to get back to the top," Falcao told United's official site.

"I am looking forward to working with Louis van Gaal and contributing to the team's success at this very exciting period in the club's history."