Two Portuguese officers among the first to investigate Madeleine McCann's disappearance yesterday blamed their superiors for allowing the initial crime scene to be contaminated by a 'circus' of people.

Breaking a six-month silence, the pair said the behaviour of senior detectives in the first few hours of the investigation had made Portuguese police an international laughing stock.

Speaking for the first time about the night of May 3, the rank-and-file officers said they looked on in horror as potential evidence trampled underfoot in Kate and Gerry McCann's holiday apartment.

Total strangers were allowed to wander in and out of the two-bedroom flat when it should have been sealed off as a crime scene, according to the duo's damning accounts.

One said: "It was chaos. The world and his dog were in that room just to look under a bed. It was crazy allowing so many people to trample through.

"There was nothing we could do. The damage had already been done."

The officers, who spoke on condition that they were not identified, arrived at the Ocean Club complex within two hours of Mrs McCann raising the alarm that Madeleine, then approaching her fourth birthday, was missing.

Referring to the senior detectives, one of the men said: "They know they mucked up. They regret it because now the whole world's laughing and pointing fingers in disgust, saying how incompetent the Portuguese police are.

"The world's eyes are on us and we mucked up big and there's nothing they can do to change things - it's too late."

Both men are officers in the Guarda Nacional Republicana, the Portuguese force which acts as the country's rank-and-file police.

The duo, who between them have 35 years' experience, said they were horrified by what they found at the apartment in Praia da Luz.

Other GNR officers and their superiors had allowed the McCanns, their friends, other police officers and total strangers to walk through it and even pick up items.

One officer told the Mail: "It had been completely compromised before we arrived.

"There was nothing to protect. It should have been done.

"To arrive as back-up and find a circus walking in and out of a possible crime scene, well... it's ridiculous."

His colleague added: "It's not brain surgery and probably, in this case, could have saved a lot of speculation, heartache and unnecessary investigation time and money."

The pair said "hysterical civilians" were running in and out of the apartment, and said their colleagues had called the Policia Judiciaria - the country's equivalent of the CID - because they felt "something wasn't right".

One said of the McCann group: "They were upset, panicking, wideeyed, the usual, but there was something else.

"They were scared - not the usual scared, they were jumpy, nervous. It wasn't normal. None of it was normal.

"They'd all been drinking. They weren't falling over but it was hard to deal with them. They were hard to get sense out of."

Mr and Mrs McCann, both 39, and their seven friends have always denied any involvement in Madeleine's disappearance.

But one of the officers said he thought the parents would be "suspects for ever" because of the bungled investigation.

He said: "This case has no end. It'll get filed away with an open verdict. The parents will be suspects for ever."

In a telling insight into opinions within Portugal's police forces, his colleague added: "They left their babies alone every night. Now they'll forever be known as 'that couple who got away with it'. That's a fair price."