The number of reported hate crimes against Muslims in the capital rose from one to eight per day in the wake of the murder of soldier Lee Rigby in Woolwich, the Metropolitan Police Commissioner has said.

Speaking in a web chat, Britain's most senior police officer Sir Bernard Hogan-Howe said that since then the number of reports has dropped again to two per day.

Drummer Rigby was murdered by Muslim extremists as he returned to Woolwich barracks in south east London on May 22.

In the wake of his death concerns were raised about a potential anti-Islamic backlash, and there was a rise in the number of reported hate crimes across the country.

There were also arson attacks at an Islamic centre in Grimsby, and a Muslim community centre and boarding school in different parts of London.

When asked whether there are additional security arrangements in place ahead of Ramadan, Sir Bernard said: "Following the terrible murder of Lee Rigby in Woolwich we did see a rise in the number of reported hate crimes against Muslims from one a day to eight a day.

"This lasted for around two weeks and has recently reduced to around two a day. There are two arson attacks which are always serious as people's lives are put at risk.

"As a result we have had 24-hour police guarding of some high risk sites over the last few weeks and extra patrolling. We are reviewing the situation every week across London and will take appropriate action to keep people safe."

In the days after Drummer Rigby's death, anti-extremist group Faith Matters said it had seen around 150 reports of hate crimes in a few days, compared to the normal rate of four to eight cases per day.

Police across the country also made a number of arrests over alleged malicious comments on social networking sites.

In London the first arson attack was at the Bravanese Community Centre in Muswell Hill which was burned to the ground on June 5. The building was found to have been daubed with the letters 'EDL', but far-right group the English Defence League denied any involvement.

The second targeted Darul Uloom Islamic School in Foxbury Avenue, Chislehurst, south east London, where nearly 130 pupils and staff had to be evacuated.

Teachers managed to extinguish the flames and two pupils were treated for smoke inhalation but did not need to be taken to hospital.

Grimsby Islamic Cultural Centre was hit with petrol bombs on May 26, and no one was hurt in the blaze.