Sarah Jessica Parker's 11 year marriage to Matthew Broderick has been hit by claims he had an affair with a 25-year-old youth worker.

American magazine Star alleges the actor had a liaison with the unnamed woman from November to February while Sarah was shooting the big screen film, Sex And The City.

Broderick's spokesperson Simon Hall didn't deny the allegations, telling the magazine instead: 'There will be no comment.'

Claims: A US magazine alleges Matthew Broderick, pictured here with wife Sarah Jessica Parker in New York in May, had an affair with a 25-year-old woman

The publication reports the pair met in a Manhattan bar last November and later he was allegedly seen heading to the woman's apartment carrying wine and flowers.

It claims Broderick, 46, told the brunette his relationship with Parker, 43, was 'not good'. 

Parker, who has a five-year-old son, James Wilkie, with the star, has previously admitted that their marriage is tumultuous at times.

Family time: The couple on a holiday with their son James Wilkie in December, the time of the alleged affair

In an April interview she said, 'I'm really lucky that he is the father of my son, but that doesn't mean that we always agree on everything. We've had some rather treacherous train rides.

'I'm happy to be with him regardless but I'm sure there are many times he wishes he wasn't with me.'

Broderick, 46, found fame with his blockbuster hit Ferris Bueller's Day Off in 1986, and most recently has starred in a series of Broadway shows including How to Succeed in Business Without Really Trying and The Producers.

Parker, who previously dated Robert Downey Jr. and John Kennedy Jr., married Broderick in May 1997 after five years together.