David Cameron took aim at Nick Clegg today as he insisted the Liberal Democrats n eed to "pull their weight" on ensuring there are more female Cabinet ministers.

The Prime Minister was challenged by Labour to explain why only three of the 22 Government departments are run by women.

But Mr Cameron, sitting next to Deputy Prime Minister Mr Clegg, turned on his coalition partner in Prime Minister's Questions as he told the Commons: "What I said is I wanted to see a third of my front bench ministers being women at the end of a Conservative government.

"We have made some important progress in terms of the numbers of people on the front bench.

"I have to say, with respect to my coalition partner, that in terms of Cabinet numbers the Liberal Democrats need to do a bit more to pull their weight on this issue.

"But I hope to be making further progress."

The number of female Cabinet members is lower now than it was when the coalition came to power.

In 2010, there were five women members of the Cabinet, although at that time no others had the right to attend the meetings.

Home Secretary Theresa May, International Development Secretary Justine Greening and Northern Ireland Secretary Theresa Villiers are the only female full members of Mr Cameron's top team.

They are all Conservative MPs.

Lib Dem Business Minister Jenny Willott became the first woman from the party to sit at the Cabinet table this week, although she does not have voting rights.

Tory Treasury Minister Nicky Morgan also attends Cabinet.

Mr Cameron was replying to a question from s hadow minister Catherine McKinnell.

She told the PM: "You promised by the end of this Parliament a third of your cabinet would be women.

"We know that the former culture secretary (Maria Miller) had to go but we now have only three out of 22 of your departments run by women.

"Do you agree with the new Culture Secretary (Sajid Javid) that this is because Government appointments should always be made on merit?"

Lib Dem Lorely Burt (Solihull) later told Mr Cameron: "Could I gently tell you that Liberal Democrat women not only pull their weight but are perfectly ready and willing to punch above their weight."