Manchester United have completed the shock signing of Colombia striker Radamel Falcao from Monaco on a season-long loan, the Premier League giants announced in the early hours of Tuesday morning.

"MUFC is delighted to announce Radamel Falcao has joined on a 1-year loan from Monaco with an option to buy," United announced on their Twitter account, alongside a picture of the player posing with a club shirt.

United have reportedly paid Monaco around 10 million euros ($13.1 million) to secure Falcao's services for the season, with an option to make the deal permanent for another 55 million euros.

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

The prolific 28-year-old forward, who missed the World Cup due to a serious knee injury, flew into Manchester to complete a medical examination hours before the transfer window closed on Monday evening.

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

Van Gaal described Falcao, who is under contract with Monaco until 2018, as "one of the most prolific goalscorers in the game".

He added: "His appearance-to-goal ratio speaks for itself and, when a player of this calibre becomes available, it is an opportunity not to be missed."

United had earlier announced the arrival of versatile Netherlands international Daley Blind from Ajax in a deal reportedly worth around £14 million ($23 million, 17 million euros).

They also sold home-grown England forward Danny Welbeck to Arsenal for around £16 million and allowed Mexican striker Javier Hernandez to join Real Madrid on a season-long loan with an option to buy.

Meanwhile, youngsters Nick Powell and Tom Lawrence both joined Leicester City on Tuesday -- Powell on loan, Lawrence on a permanent four-year deal -- while 21-year-old defender Michael Keane was loaned to Burnley.

Falcao, who has scored 20 goals in 51 appearances for Colombia, has already found the net twice for Monaco this season after making his comeback from a ruptured anterior cruciate ligament.

He will hope to win a place in United's attack alongside Robin van Persie and Wayne Rooney, leaving Van Gaal with a rich pool of striking talent at his disposal.

United are rebuilding after a disappointing seventh-place finish in the Premier League last season and have spent around £150 million on new players, including a British-record £59.7 million move for Angel di Maria.

They have also signed Spanish midfielder Ander Herrera, England left-back Luke Shaw, and Di Maria's Argentina team-mate Marcos Rojo.

Van Gaal is still waiting for his first competitive win as United manager, after two draws and a defeat in the league and a humiliating 4-0 loss to third-tier Milton Keynes Dons in the League Cup.

After making his name with Argentine giants River Plate, Falcao signed for Porto in 2009 and established himself as one of Europe's most lethal marksmen by scoring 72 goals in 87 games.

He won the Portuguese Cup in his first season and helped Porto to a treble of league, cup and Europa League honours in 2011, scoring the only goal in the Europa League final against Braga.

A move to Atletico Madrid followed later that year and he won the Europa League again in his first season, scoring twice as Diego Simeone's side overcame Athletic Bilbao 3-0 in the final.

Falcao joined Monaco from Atletico last year in a deal worth around 60 million euros, having scored 70 goals in 91 games during his time in Spain.

He scored nine goals in his first 17 league games with Monaco, but his debut season was curtailed in January when he damaged his knee in a French Cup tie, forcing him to miss the World Cup.