Image copyright Reuters Image caption Downing Street said David Cameron has the "greatest of respect for Conservative associations"

Dozens of Tory members have accused David Cameron of showing disrespect to the party's grassroots after he told MPs to disregard their views on Europe.

In a letter to the Sunday Telegraph, the signatories from more than 40 Conservative associations said their opinions should be heard.

They said it was "deeply regrettable" that the PM had dismissed their views.

Downing Street told the newspaper that the prime minister had the "greatest of respect for Conservative associations".

"He was simply making the point that everyone should ultimately vote with their conscience," a spokesman said.

An in-out referendum on EU membership has been promised by the end of 2017, although it is widely expected to be at the end of June, if Mr Cameron can secure agreement to his reform proposals at the next summit of EU leaders on 18 February.

The PM said last week that MPs should not vote based on what their constituency association might say, and instead vote with their heart.

'Loyal servants'

However, the associations' letter said: "It was through the dedication and hard work of Conservative Party members that David Cameron secured the majority he needed to form a government...

"It is deeply regrettable that the prime minister dismisses the very people who helped secure his victory, and he should remember that no prime minister has a divine right to rule."

In the letter they urged Mr Cameron to "accept that loyal Conservative Party members want the opportunity for a balanced debate".

Among the signatories are Ed Costelloe, chairman of Grassroots Conservatives, Matt Ewert of the South Staffordshire Conservative Association, Tony Partridge of the Clwyd South Conservative Association and Geoffrey Vero of the Surrey Heath Conservative Constituency Association.

Image caption UKIP MP Douglas Carswell wants an 'internationalist' exit campaign

Housing Minister Brandon Lewis said local Tory associations "care passionately about their local ability to make decisions" but the PM had stressed everyone would have their say at the referendum.

The letter comes amid continued speculation about whether a big cabinet name will lead the campaign to take Britain out of the EU when Mr Cameron announces the date of the referendum.

Home Secretary Theresa May is thought to have ruled herself out, and Mr Cameron is hoping to persuade London Mayor Boris Johnson to back him.

A spokesman for Justice Secretary Michael Gove said he "supports the prime minister's strategy to renegotiate our relationship with the European Union" and it would be "premature" to make a judgement before the deal is concluded.

A source close to Work and Pensions Secretary Iain Duncan Smith said he would "make his views known when he's seen the final deal".

A spokesman for Employment Minister Priti Patel, who has been at the centre of press speculation that she will lead the exit campaign, said she had "always said she would make a judgement once we've seen the final deal".

'Optimistic campaign'

UKIP MP Douglas Carswell told the BBC's Andrew Marr programme it "would be wonderful" to have a Eurosceptic cabinet minister fronting the exit campaign but it needs and welcomes anyone who wants to join it.

He refused to enter into the war of words between the rival groups vying to be designated as the official Leave campaign, but ruled out a merger between them saying there were fundamental differences on tactics.

The UKIP MP said Leave.EU, which is backed by UKIP donor Arron Banks, wanted to focus on "identity and immigration," while Vote Leave, which he supports, wants to put forward an "optimistic, upbeat internationalist message".

A third group, Grassroots Out, which was founded by two Conservative MPs and is backed by UKIP leader Nigel Farage and Mr Banks, has said it is exploring whether it has enough cross-party support to make a bid to be the official Leave campaign.

Lib Dem Leader Tim Farron, who wants Britain to remain in the EU, said both the leave campaigners and the prime minister were failing to concentrate on the "big questions" that people would be thinking about when they voted in the referendum.