Image copyright Labour Party Image caption The vehicle will aim to visit more than 70 constituencies before 7 May

Labour has defended the choice of a pink minibus to launch a campaign aimed at female voters after it was attacked on social media.

Deputy leader Harriet Harman is leading the "woman-to-woman" initiative, which will see a 16-seater minibus tour the UK up to May's election targeting women who did not vote in 2010.

She said it would demonstrate politics was not just a "men-only" activity.

She defended the van's livery, joking "is it not magenta or something?"

But the choice of colour and the size of the vehicle attracted criticism on Twitter.

'Something different'

At a briefing for Westminster journalists, Ms Harman said that while Labour would be highlighting policies on issues such as childcare and domestic violence, David Cameron and the Conservatives had nothing to offer female voters.

"We don't want women to give up on politics," she said. "If you look at the figures, the disaffection that there is with politics is even more pronounced among women.

Image copyright PA Image caption Ms Harman said it was Labour's first "proper" campaign aimed exclusively at women

"We want women to feel that this is their democracy and politics is for them as well as for men. Politics is too important to be left to be a men-only activity. We are saying this is a woman-to-woman activity."

More than nine million women who are eligible to vote did not vote at the last general election five years ago.

While Ms Harman rejected suggestions that the campaign was "patronising" to women, she was reluctant to be drawn on the choice of a pink bus, saying that the colour had been picked by "a collective".

By the BBC's Johanna Howitt

When is pink not pink? When it is magenta?

At a media briefing this afternoon on Labour's Woman to Woman campaign, Harriet Harman seemed keen to make sure we all knew the precise colour of the team bus.

She described the detailed discussions in choosing the colour.

"We wanted it to be red…", she said, pointing to a Labour backdrop, "…but then it looked the same as everything else.

"We then looked at a darker red, but that looked too much like a Pret delivery van. We wanted to be visible and conspicuous, to mark it out, to be different".

Earlier, she also referred to the hue as "a One Nation colour". So it would seem you can call it anything - just not pink.

Oh, and to be clear - it's a "16 seater". By my measure that's a mini bus… but I'm no expert.

"Is it not magenta or something?" she joked. "We wanted to mark that this was something different. We wanted it to look conspicuous and therefore a white van was not going to do the job."

She added: "It is a very nice looking bus.... It is the correct colour. This is a One Nation Labour colour."

'Gimmick'

But Kevin Maguire, political editor of the Labour-supporting Daily Mirror, was among journalists to question the choice of colour.

Image caption Labour said the colour was the same as that used in September's party conference

He tweeted: "Pink? PINK? I'd have expected Harriet Harman to demand a blue election battle bus to fight gender stereotypes."

And the Conservatives said they would not be following suit.

"Getting Harriet Harman to drive around the country in a pink van to try and attract the female vote is as patronising as it gets," said backbench MP Caroline Dinenage,

"This is clearly just another divisive gimmick that the electorate will see through".

And the Lib Dems said "women voters won't forget Labour's car crash record on the economy just because Harriet Harman turns up in a pink van".

Responding to the criticism, Labour's women's and equalities spokesman Gloria De Piero said the van's livery was "the same colour" as the party had used as the backdrop for its 2014 autumn conference in Manchester.

She tweeted: "Glad everyone is talking about the Labour women's bus!"