Diouf, who is on loan from Liverpool, was fined two weeks wages for the incident at the Reebok Stadium.

"I deeply regret my actions and wish to publicly apologise to Arjan de Zeeuw and Portsmouth Football Club," Diouf said on the club's website.

"I have let down my manager, Sam Allardyce, and team-mates.

"I am a role model to many thousands of fans throughout the world and my behaviour showed a lack of moral responsibility to the public who support me.

"I am deeply sorry and embarrassed about the incident."

It is not the first time Diouf's spitting has landed him in trouble.

Glasgow Sheriff Court fined the forward 5,000 pounds (7,130 euros, 9,460 dollars) for spitting at Celtic fans during Liverpool's UEFA Cup tie at Parkhead in March 2003.

And Cleveland police started an investigation after Diouf was accused of spitting at a Middlesbrough supporter during Bolton's match at the Riverside on November 7.

A combined statement from chairmab Phil Gartside and Allardyce said: "The club does not tolerate such behaviour from its players and we had no alternative but to evoke the maximum fine against El-Hadji Diouf.

"Bolton Wanderers takes great pride in its very proactive family image and yesterday's incident has left a sour taste.

"We do not condone the actions taken by the player and for that he has been severely punished."