"This weekend a series of even more absurd and unsubstantiated claims have been published about David and Victoria Beckham," the statement said.
"The couple continue to dismiss these stories and they will not be commenting upon them further at this time. Lawyers have been instructed by David and Victoria concerning these matters," said the statement, released by management agency 19, which represents the couple.
Last week, the News of the World tabloid reported that Beckham, 28, had a sexual relationship with his personal assistant Rebecca Loos, 26, between September and December.
Beckham issued a statement describing the Loos story as "ludicrous," but that did nothing to dampen media frenzy. When the Beckhams retreated to the French Alps for a skiing holiday last week, the newspapers followed them, looking for signs of strife or reconciliation.
On Sunday, Malaysian-born model Sarah Marbeck, 29, was quoted as telling the News of the World she had sex with Beckham hours after meeting him in Singapore in July 2001. She said they spent their second and last night together in March 2002.
She claimed they called and sent mobile phone text messages to each other for at least a year, before they lost touch.
Beckham, who played for Manchester United, moved to Spain last summer to play for Real Madrid.
Victoria Beckham spends most of her time in England with the couple's two young sons, 5-year-old Brooklyn and 18-month-old Romeo. The former Spice Girl has been trying to rekindle her flagging pop career.