British police helped "develop" evidence against Madeleine McCann's parents as they were investigated by Portuguese authorities looking into their daughter's disappearance, according to diplomatic cables published by WikiLeaks.

Britain's ambassador to Portugal, Alexander Wykeham Ellis, reportedly made the claim to his American counterpart on September 21, 2007 - two weeks after Portuguese police named Gerry and Kate McCann as "arguidos", or formal suspects, in the case.

In a cable to Washington, US Ambassador Al Hoffman wrote: "Madeleine McCann's disappearance in the south of Portugal in May 2007 has generated international media attention with controversy surrounding the Portuguese-led police investigation and the actions of Madeleine's parents.

"Without delving into the details of the case, Ellis admitted that the British police had developed the current evidence against the McCann parents, and he stressed that authorities from both countries were working co-operatively.

"He commented that the media frenzy was to be expected and was acceptable as long as government officials keep their comments behind closed doors."

The cable does not specify what evidence British police are alleged to have gathered, or whether UK investigators were involved in the decision to formally name the McCanns as suspects.

They remained under official suspicion until July 2008 when Portuguese police shelved the investigation into Madeleine's disappearance and lifted the McCann's status as arguidos.

The three-year-old went missing from an apartment in the Algarve on May 3, 2007 while her parents dined with friends in a nearby restaurant.

Speaking at the time the suspect status was lifted, Mrs McCann said: "It is hard to describe how utterly despairing it was to be named arguidos and subsequently portrayed in the media as suspects in our own daughter's abduction."

A spokesman for the McCanns said: "This is an entirely historic note that is more than three years old. Subsequently, Kate and Gerry had their arguido status lifted, with the Portuguese authorities making it perfectly clear that there was absolutely no evidence to implicate them in Madeleine's disappearance whatsoever. To this day, they continue to work tirelessly on the search for their daughter, co-operating when appropriate with both the Portuguese and British authorities."