A friend of Madeleine McCann's parents attacked the "outrageous" conduct of Portuguese police on Thursday over their investigation into the missing girl.

In her first public comments, Rachael Oldfield - one of the so-called "Tapas Seven" group -- accused police of double standards over what she said was their constant leaking of details about the investigation despite strict secrecy laws.

Her attack, during a radio interview to be broadcast on the BBC on Thursday, comes less than a fortnight after Kate and Gerry McCann denounced the police for undertaking what they described as a smear campaign against them.

Earlier this month, a Spanish television station broadcast leaked police witness statements that said the missing girl had asked her parents the night before her disappearance why they did not come into her room when she and her twin brother and sister were crying.

The McCanns remain official suspects in their daughter's disappearance from the Algarve resort of Praia da Luz last May but deny any wrongdoing.

Oldfield, one of the group who dined at a Tapas bar with the McCanns on the night Madeleine went missing shortly before her fourth birthday, accused police of double standards.

"They leaked information and these rumours that have flown around for the past year," the 36-year-old said in extracts broadcast on BBC radio. "It is outrageous. We have all felt very angry about it.

"We were asked to comply with the Portuguese judicial secrecy laws, which we were made to understand that we could face two years in prison for speaking out," she said.

"So as a group, we have not said anything from day one."

The family's official spokesman, Clarence Mitchell, was not immediately available for comment, but he has previously called for an investigation into the leaks.