A retired Portuguese detective who wrote a book claiming Gerry and Kate McCann covered up the death of their daughter, Madeleine, has received more than £50,000 in donations from the UK to defend a libel action brought by the couple.

Some have come from self declared “trolls” who have thrown their support behind Goncalo Amaral, 57, who was ordered by the Portuguese courts to pay Mr and Mrs McCann £357,000 damages, after being sued for defamation by the couple.

The award was overturned last month, but that decision is being challenged by the McCanns at Portugal’s supreme court.

Now Mr Amaral, who was sacked as head of the investigation after criticising British police, is being helped by a crowdfunding site which was started by Leanne Baulch, a psychology student last April.

It was closed last October after declaring that sufficient funds had been raised.

The Daily Mail reported that donors included a number of serving Metropolitan Police officers who gave £1,000 to the fund.