British police spent more than half a million pounds assisting the Portuguese investigation into Madeleine McCann's disappearance, it was revealed today.

Leicestershire Police's part in the search for the missing little girl cost £548,477 in 2007-08, the force said.

But it was reimbursed for most of this amount thanks to a Home Office grant of £525,069.

The Policia Judiciaria - Portugal's CID - led the investigation into Madeleine's disappearance from the Algarve village of Praia da Luz on May 3 2007.

Leicestershire Police became involved in the case as the home force of the child's parents, Kate and Gerry McCann.

British officers, headed by Detective Superintendent Stuart Prior, conducted interviews of witnesses in the UK and passed possible sightings of Madeleine on to their Portuguese colleagues.

After a lengthy delay Leicestershire Police responded today to a Freedom of Information request for information about its role in the case.

It said: "The total additional expenditure incurred for 07-08 was £548,477 and Leicestershire Constabulary received a Home Office grant of £525,069."

The force refused to provide a breakdown of where the money was spent because this would reveal "operational, investigative and law enforcement techniques.

Madeleine was nearly four when she went missing from her family's holiday apartment in Praia da Luz while her parents dined with friends nearby.

Despite a massive police operation and huge publicity worldwide, she has not been found.

Four months after she disappeared, on September 7 2007, Portuguese police made both Mr and Mrs McCann "arguidos", or formal suspects, in the case.

Two days later the couple flew back to their home in Rothley, Leicestershire, with their two other children, twins Sean and Amelie.

Last July the Portuguese attorney-general shelved the investigation and lifted the McCanns' arguido status.

The following month, thousands of pages from the official Portuguese police files were made public, revealing the many different lines officers pursued in their 14-month inquiry.

Mr and Mrs McCann, who say they will believe Madeleine is alive until given clear evidence to the contrary, have had the documents translated into English to help them search for their daughter.

It is understood they are being assisted by a small team that includes retired senior British police officers and former security service officials.