Conservative leader David Cameron has called for more accountability of police forces, days after West Midlands Police and prosecutors paid out a six-figure sum for wrongly claiming a television expose of Islamist extremists was faked.

Mr Cameron, who was in Birmingham launching a major policy initiative on public spending, said that a Channel 4 Dispatches programme exposing hate-filled teachings in a Birmingham mosque was a "worthwhile piece of work".

The broadcaster received £100,000 when it launched libel proceedings against police and the Crown Prosecution Service after it was reported to TV watchdog Ofcom for "heavily editing" the words of Islamic imams to give them more sinister meaning.

Mr Cameron said: "What I want to see is an elected police commission. Not elected police chiefs - but commissioners that will ensure with an elected mayor that the police are accountable. We do not know who police authority members are or what they do, so as a result we do not get police forces that are held responsible for their actions.

"Many of us who watched the programme (Dispatches) were interested in what it had to say on the very real threat of extremists in our society. It was a worthwhile piece of work. It was something that was worth knowing about.

"This issue tells us that the police need to be careful and more considered about things."

The programme, called Dispatches: Undercover Mosque, investigated several mosques including Green Lane Mosque, in Small Heath.

Abu Usamah, one of the preachers from the Mosque who was featured in the programme, said he was shocked when he saw himself depicted. "It was the fact that Green Lane Mosque has a 33-year-old tradition of preaching and teaching the moderate version of Islam," he said at the time.

West Midlands Police also claimed the programme undermined "community cohesion" and "feelings of public reassurance". However, they were forced to back down in court last week.

Around 100 Conservative supporters listened to Mr Cameron’s speech in Birmingham at The Studio, in Cannon Street, including local councillors and business leaders. Mr Cameron ended his speech by congratulating the Birmingham and Solihull Conservatives for their success in the recent local elections.

He also said that there would be plenty of Tory candidates in Birmingham capable of winning a directly elected mayor contest similar to the one that was won by Conservative candidate Boris Johnson in London earlier this month.

He said: "We have already won in Birmingham. We won six seats in the elections in the Birmingham area. We have done extremely well. We have politicians of a calibre who could succeed in Birmingham.

"We will encourage people from the business community to come forward, I am sure there are some very good leaders in Birmingham. You have a very strong civic history. Every time I walk past the statue of Chamberlain I am reminded of that. So I am sure we will find the calibre of leader to lead the city."

He said he was a "huge fan" of elected mayors, adding: "If you look at the turnout in London, where they had people queuing around the block to vote in the election, this proves that this idea works even if it is just to encourage people to get involved in politics."

Mr Cameron also told supporters that he would be voting in favour of "admix embryos" and the creation of "saviour siblings".

He said: "My own approach to this is the law needs updating and the importance of science and research and getting to grips with genetic disease ... I want to see the research go forward."

However, he said he would be voting "against some of the things that won’t be necessary". He said he also wanted to see the abortion limit reduced.