Ralf Mutschke. Photo: Getty Images

The third round of World Cup group matches will be closely scrutinised for potential match-fixing, football's world governing body Fifa has said.

Head of security Ralf Mutschke believes these first-stage games have a "higher vulnerability" of being targeted.

He said spot-fixing - betting on individual elements of matches - is a danger in 'dead rubber' matches, with little at stake on the result.

"This is part of our risk management strategy," said Mutschke.

Fifa's 13-man technical study group - which includes the former Liverpool manager Gerard Houllier and Finland boss Mixu Paatelainen - has been enlisted to watch out for any suspicious activity it observes.

Mutschke said: "We also look at a level of higher vulnerability in the closing matches at the end of each group when some teams already know what will happen.

"The members of the technical study group are additional eyes and ears so we involve them in the discussions about whether match manipulation took place or not."

Fifa says it monitored 98 pre-tournament friendlies and witnessed no abnormal betting activity or suspicious behaviour within the matches.

Scotland's game against Nigeria at Craven Cottage in May was subject to a warning from the National Crime Agency over a potential risk of the game being targeted by gambling syndicates.