The Dutch football federation (KNVB) on Saturday opened a match-fixing inquiry after claims that first division side Willem II had rigged the results of two matches, including one against giants Ajax.

"Given the gravity of the facts described we are going to lodge legal action so that a criminal investigation can be opened into this affair," the KNVB announced.

A report in Dutch daily De Volksrant claimed players from Willem II were paid by a Singapore betting ring to fix games against Ajax in October, 2009, and Feyenoord two months later.

Willem lost 4-0 to Ajax and 1-0 to Feyenoord.

The KNVB described the accusations as "the most serious up to now in the Netherlands".

Willem II for their part said they were "shocked and surprised" at the allegations.

"We will naturally assist as much as possible with any eventual investigation in order to unearth the truth"," a club statement announced.

The paper identified the ringleader amongst the Willem II players as Sierre Leone's Ibrahim Kargbo, who allegedly recruited his teammates for the scam.

De Volksrant says Kargbo, who now plies his trade in the Portuguese second division, and his teammates split 100,000 euros each for orchestrating the two results.

Kargbo denied the accusation, telling the paper: "I've never received money, from anyone."

The player in the spotlight was suspended by Sierra Leone over previous claims of match-fixing against South Africa in qualifiers for the 2010 World Cup and Africa Cup of Nations.