Barnet's senior policeman has urged people not to seek revenge for Thursday's attack by indiscriminately targeting Muslim people in the borough, and appealed for calm.

Despite the plea, there were nine reported racist incidents between Friday and Monday, the most serious of which was a phone call made by a man from a phone box in Hillingdon on Friday evening, threatening to bomb Hendon Islamic Centre and Mosque, in Brent View Road, West Hendon.

Borough Commander Chief Superintendent Mark Ricketts said: "People are using Thursday's attack as an excuse to vent pre-existng hatred against minority groups. It will not be tolerated. This is a priority for us."

Of the nine incidents reported to police, five have taken the form of racist abuse against Asian people. Two of them have been anti-Semitic (bizarrely blaming Jews for the bombs) and one case anti-American and anti-British abuse at a police operator. Nobody has yet been arrested.

Chief Supt Ricketts said there are no specific threats' to the borough, but added guardedly: "Barnet has been a target in the past. I would be foolish not to believe that if further terrorism was to take place elsewhere, it could be north or south of the river.

"My intention is to make Barnet as hostile an environment to the terrorists as we possibly can."

Since the bombings on Thursday, Chief Supt Ricketts has deployed officers around the main transport hubs in the borough, like Golders Green Tube and bus station, Edgware and High Barnet Tube stations, as well as what he calls postcard sites' such as the RAF Museum in Hendon.

He said: "For reassurance we've put out 90 officers over each 24-hour period. The key message is about reassurance. As people make the decision to get on with their lives, then it's our role to support them and give them confidence to do it. Visible patrols are also a deterrent to terrorists."