The 28-year-old Gambian international, who can play on either wing or in the centre of midfield, joined Walsall last summer and made 37 appearances.

Sonko told the Tranmere website: “I had the choice of three or four clubs but I saw Tranmere as a progressive and ambitious club.

“I think my speed and directness will add pace to the team.”

Sonko was not offered a new contract by Walsall at the end of last season.

Tranmere manager Ronnie Moore said: “I’m delighted to sign Edrissa, he’s a talented player.

“He has bags of pace and the tricks to beat a defender, he’s played across Europe and at international level.”

Sonko began his career at Real de Banjul, in his home country, before moving to Belgian first division side Anderlecht in 1999.

He moved to Dutch side Roda JC in 2000 before having a short spell at Greek side Xanthi in 2007.

And Sonko told BBC Radio Merseyside he is now hoping to make his debut in Saturday’s friendly against Liverpool.

“It’s going to be a big game and a tough encounter. We will try to learn from it,” he said.