Counter terrorism officers are investigating after letters containing white powder were sent to mosques across London.

Security alerts were sparked at mosques in Tottenham, Leyton and Finsbury Park after the letters, including one scrawled with the words "P*** filth", arrived yesterday.

The letters arrived on the same day parts of Parliament were shut down by police after a Muslim Labour peer, Lord Ahmed, received a similar package at the House of Lords.

A business address in Canning Town was also sent the powder.

The envelope sent to Tottenham's Masjid Ayesha mosque was filled with white powder and had the words “P*** filth” scrawled on the outside.

It also contained an image of a mosque which had apparently been drawn by hand and then crossed out.

Specialist police officers in hazard suits and breathing apparatus were called to the scene as the mosques were closed down and evacuated as they examined the powder.

The powder reportedly left a member of staff feeling “itchy” at Masjid Ayesha. It was found to be non-toxic. A worshipper said he understood the powder was chalk.

Leyton mosque Noor Ul Islam received a similar delivery containing white powder and “offensive language” on Thursday.

The Muslim Welfare House in Seven Sisters Road, Finsbury Park, faced a similar alert, while a business address in Bidders Street, Canning Town, was also targeted.

Walthamstow MP Stella Creasy condemned the incident in Leyton this morning, tweeting: "Whoever sent E10's noor Ul Islam suspicious package know I will press the police for the strongest penalties possible when you are caught."

A worshipper at Masjid Ayesha, in Clyde Road, wrote on Facebook: “A committee member from the mosque called the police after his dad felt itchy from the white powder.

“The police then called a bomb squad to examine the crime scene… The white powder was just chalk.”

He added: “What was alarming however was how the police had been to six other mosques today [which] were sent the exact same type of package.”

He added: “Someone somewhere is trying to send the Muslim community in the UK a message. And whether we like it or not Islamaphobia is real.”

Staff at the Noor Ul Islam, in Leyton High Road, sought to reassure worshippers.

They wrote on Facebook this morning: “On 7th July the Noor Ul Islam head office received an envelope in the post that contained white powder and offensive language.

“Specialist officers attended and the contents of the package were examined. They were found to be not noxious or suspicious.

“It appears that similar envelopes were received on 7th July at other locations. Police enquiries continue.”

Today London mayor Sadiq Khan today launched crackdown on hate crime on public transport following a spike in racist abuse.

It came after Met Police Commissioner Sir Bernard Hogan-Howe confirmed there had been a 52 per cent rise in complaints since the poll.

It is thought six mosques were sent the powder but the exact number affected is not clear.

Police said the investigation was being dealt with by a counter terror unit in the North East after similarities to an incident in south Yorkshire.