British police are partly responsible for the radicalisation of three sisters thought to have taken their children to join extremists in Syria, it has been claimed.

Mohammed Shoaib and Akhtar Iqbal, whose wives both left their homes in Bradford to travel to Syria, suggested that police encouraged their radicalisation by urging the women to contact their brother who had already left for Syria. It is believed he is fighting for with the Isis terror group.

In a letter to Keith Vaz, chairman of the Home Affairs Select Committee, and the Home and Foreign Secretaries, lawyers for the two husbands said that “plainly the North East Counter-Terrorism Unit (Nectu) has been complicit in the grooming and radicalising of the women,” the Mail on Sunday reported.

The letter claims that “the actions and misjudgement of Nectu have placed the lives of 12 British citizens at risk”. The accusations have been rejected by both MPs and Downing Street.

In pictures: Fight for Tikrit Show all 16 1 /16 In pictures: Fight for Tikrit In pictures: Fight for Tikrit Fight for Tikrit Shiite fighters pose in front of a mural depicting the emblem of the Islamic State group outside one of the presidential palaces in Tikrit, on April 1, 2015 Getty Images In pictures: Fight for Tikrit Fight for Tikrit Iraqi Prime Minister Haider al-Abadi tours the city of Tikrit after it was retaken by the security forces in Baghdad, Iraq, on April 1 2015 AP In pictures: Fight for Tikrit Fight for Tikrit An Iraqi flag waves over the Tigris River om April 1 2015 AP In pictures: Fight for Tikrit Fight for Tikrit Iraqi security forces playing football in Tikrit after their country declared a 'magnificent victory' over the Islamic State group in the city on April 1 2015 Reuters In pictures: Fight for Tikrit Fight for Tikrit A member of the security forces holds Iraq’s national flag in front of a painted Isis emblem Getty Images In pictures: Fight for Tikrit Fight for Tikrit Iraqi security forces arrest a member of the Islamic State in Tikrit on April 1, 2015 Reuters In pictures: Fight for Tikrit Fight for Tikrit A member from the Iraqi security forces beats an Isis insurgent, who was captured in Tikrit Reuters In pictures: Fight for Tikrit Fight for Tikrit Shiite fighters from the Popular Mobilisation units celebrate in front of the the provincial council building inside the northern Iraqi city of Tikrit on March 31, 2015 Getty Images In pictures: Fight for Tikrit Fight for Tikrit Iraqi soldiers stand on a damaged tank during fighting against IS militants near Tikrit Corbis In pictures: Fight for Tikrit Fight for Tikrit Fighters of Iraqi Shiite militias who volunteered to support the Iraqi forces make their way towards Daquq town near Tikrit Corbis In pictures: Fight for Tikrit Fight for Tikrit Iraqi security forces and Shia fighters chant slogans as they gather at Udhaim dam, north of Baghdad, where they have been massing in preparation for an attack on Isis along the Tigris River Reuters In pictures: Fight for Tikrit Fight for Tikrit Pro-government volunteer Shia fighters in Awaynat near Tikrit AFP/Getty In pictures: Fight for Tikrit Fight for Tikrit Iraqi government forces and allied militias firing weaponry from a position in the northern part of Diyala AFP In pictures: Fight for Tikrit Fight for Tikrit A volunteer in the Iraqi Shiite Badr Army militia taking up position outside Tikrit Corbis In pictures: Fight for Tikrit Fight for Tikrit Volunteers of the Iraqi Shiite Badr Army militia patrol an area at eastern Tikrit city Corbis In pictures: Fight for Tikrit Fight for Tikrit Members of the Iraqi security forces coming from the city of Samarra drive towards al-Dawr south of Tikrit to launch an assault against the Islamic State AFP/Getty

It comes in the aftermath of David Cameron's comments that some Muslim communities “quietly condone” extremism by not confronting it.

A No 10 spokesman said: “As the prime minister said in his speech on Friday, it is wrong and dangerous to play the blame-game, and to argue that radicalisation is the fault of someone else.

“Pointing the finger at the authorities or agencies ignores the real causes of radicalisation and how we can work together to tackle it.”

“That three women could disappear from the UK to take nine children into the heart of a war zone is incomprehensible,” Keith Vaz told the Mail on Sunday.

“The claims of their relatives in the UK that their links with Isis were ‘encouraged’ by the authorities is concerning.”

In response to the claims, West Yorkshire Assistant Chief Constable Russ Foster, of Nectu, said: “We have not seen the letter so cannot comment in detail on its contents. However, we completely reject accusations that the police were complicit in the alleged grooming of the missing family or that we were oppressive to them.

“While we do not comment on all aspects of police work for valid operational and safeguarding reasons, this is an ongoing investigation and we are continuing to do everything we can to find the missing family and to ensure the safety of the children.