The letter continued: "Incidents such as this do irreparable damage to the vital race relations work that is being done and has been done by the Government and leaders of ethnic minority communities, both at home in this country and abroad.

"We feel tremendously disappointed and hugely saddened by these events. There is no doubt that the security services must act upon intelligence and seek to defend fellow citizens.

"At the same time they must ensure that adequate evidence is available otherwise such events only make the task of defending our great country even harder.

"An important strand of counter-terrorism must be about winning the hearts and minds as well as the confidence of Britain's Muslim community.

"Events such as these undermine this effort."

The arrests took place after Bob Quick, the Met's Assistant Commissioner and Britain's most senior anti-terror officer, inadvertently revealed secret plans of the raid to Downing Street press photographers on his way to brief the Prime Minister.

Mr Quick has since resigned and police are adamant his error did not compromise the investigation.

Yesterday, Lord Carlile, who reviews terror legislation, said he had decided to look into the operation while memories were still fresh.

ends