Manchester United scouts checked on Porto striker Jackson Martinez last week.

The 28-year-old wants to leave Portugal this summer and his club will listen to offers of around £30million.

The Colombia international came close to joining AC Milan in January but the club failed to agree a fee.

Manchester United scouts checked on £30million-rated Porto striker Jackson Martinez last week

Martinez (right) scored as Porto beat Bayern Munich 3-1 in their Champions League quarter-final first leg

Martinez was outstanding against Bayern Munich in Porto's Champions League semi final first leg victory scoring in their 3-1 triumph. It was his 23rd goal in 31 games this season.

United are looking to add two strikers this summer. Burnley's Danny Ings remains an option, as reported by Sportsmail last month, and they have considered Edinson Cavani who is also a firm target for Juventus. However, Paris Saint-Germain are reluctant to sell Cavani.

Aston Villa's Christian Benteke has been discussed but no approach has yet been made.

Chelsea, Tottenham and Everton also sent scouts to watch Porto and Bayern last Wednesday while Manchester City and Juventus scouts were there to watch Alex Sandro, the Porto left-back.