Downing Street tonight denounced as ‘wrong and dangerous’ a claim that British police ‘actively encouraged and promoted’ the radicalisation of three sisters who took their children to join Islamic State terrorists last week.

The suggestion by two of the women’s husbands that the police played a part in sending them towards IS by encouraging contact with their radicalised brother in Syria was also angrily rejected by senior officers and branded ‘ludicrous’ by MPs.

Lawyers for Mohammed Shoaib, 39, and Akhtar Iqbal, 48, have written to the Home and Foreign Secretaries, and chairman of the Home Affairs Committee, Keith Vaz.

Blame game: Fathers Mohammed Shoaib (left), 39, and Akhtar Iqbal (right), 48, claim the British police 'actively encouraged and promoted' the radicalisation of three sisters who fled the UK with their nine children last week to join IS fighters in Syria

The letter said: ‘We are alarmed by the fact that the police have been actively promoting and encouraging contact with the brother-in-law of our clients whom, it is believed, is fighting in Syria.

‘It would appear that there has been a reckless disregard as to the consequences of any such contact on the families.

‘Plainly the North East Counter-Terrorism Unit (Nectu) has been complicit in the grooming and radicalising of the women.’

In the letter, a copy of which has been obtained by The Mail on Sunday, they also blamed ‘oppressive police surveillance’ for the fact that the sisters and their nine children aged three to 15, had left the UK.

It continues: ‘The actions and misjudgment of the Nectu has placed the lives of 12 British citizens at risk, nine of whom are innocent children.’

The astonishing allegation, through the men’s lawyers, came only a day after David Cameron bluntly told British Muslims that some in their community ‘quietly condone’ extremism by failing to speak out against the ‘poisonous ideology’ of Islamic State.

A No 10 spokesman said today: ‘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.

On the run: Khadija Dawood (left) and Sugra Dawood (right), two of the three sisters who fled the UK last week, were allegedly radicalised by British police, who encouraged them to make contact with their brother who is believed to be fighting with IS in Syria

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

The Prime Minister had also called on relatives to stop blaming police and the security services for failing to prevent British teenagers travelling to Syria.

He pointed out that angry young people buying into revolutionary causes was not new, but added it was easier to go from being a troubled teenager to a jihadi if extremism ‘is quietly condoned online or perhaps even in parts of your local community’.

Tory MP Peter Bone echoed Mr Cameron’s views, saying: ‘It is frankly ludicrous to accuse the police of being involved in grooming or radicalising of these women.

‘These women apparently chose to go to Syria and take their children with them. As the Prime Minister made crystal clear last week, hard-pressed police officers and the security forces can hardly be blamed for this sort of personal decision.

Pointing the finger at the authorities or agencies ignores the real causes of radicalisation and how we can work together to tackle it. Number 10 spokesperson

‘The answer must partly lie, as Mr Cameron said, in Muslim communities and families stepping up their efforts to prevent relatives from going to Syria.’

However, Mr Vaz told The Mail on Sunday: ‘That three women could disappear from the UK to take nine children into the heart of a war zone is incomprehensible.

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

It emerged last week that the women were stopped from leaving the country for Saudi Arabia in March by police, who dragged them off a plane to question them under the Terrorism Act 2000. But they were allowed to rebook the flight and go in May, as they were going on a ‘religious pilgrimage’.

In both cases, Mr Shoaib and Mr Iqbal drove their wives, Sugra and Khadija Dawood, and children to Manchester airport, without having any doubts that their spouses may flee to Syria to join their brother, Ahmed Dawood. The women were joined by their sister Zohra. The men made a tearful TV appeal on Tuesday for their wives to come back. The public appeal was picked up by media around the world.

West Yorkshire Assistant Chief Constable Russ Foster, of Nectu, hit back angrily at the claims of Mr Shoaib and Mr Iqbal, saying: ‘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, 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.

‘Their relatives have been kept informed throughout this investigation and we are pleased they expressed their satisfaction with the support they have received so far. This will continue.’

Ringleader was depressed... and wanted divorce

Grief: Zohra Dawood suffered from severe depression after her brother left to fight in Syria, according to her husband Zubair Ahmed, 43

The husband of the Bradford sisters’ ringleader, Zohra Dawood, has revealed that his wife suffered severe depression after her brother fled to Syria to fight for extremists.

Zubair Ahmed, 43, told The Mail on Sunday that his wife would cry all night. It put a huge strain on their marriage and he returned to Pakistan from Bradford.

Mr Ahmed is a first cousin of British-born Zohra, 33. The couple married in Pakistan about eight years ago. Mr Ahmed said that after slipping into depression, his wife stopped looking after their two daughters, Haafyieh Binte Zubair, eight, and Nurah Binte Zubair, five. ‘I looked after the kids, and did the housework, and she did not do anything. She just cried. This put a severe strain on our marriage, and eventually she said she wanted to divorce me,’ he said.

‘She said she needed a break. This is why I came back to Pakistan eight months ago – to save my marriage. She said she will call me when she is ready. I have not had any contact with my wife or children since I came here, and did not know that she had gone on pilgrimage to Mecca, or to Syria.’

He said his wife and her six sisters were fond of their only brother and his disappearance caused them all grief.