Ukip leader Nigel Farage has urged voters to stick by candidate Mark Reckless in the key constituency of Rochester and Strood.

Mr Farage said only Ukip could deliver a referendum on whether to stay or leave the EU and deal with immigration.

In a rally held at Rochester's Corn Exchange, Mr Farage delivered a characteristically uncompromising speech to around 300 people.

He said: "If you want a referendum to happen, and you want it to be fair, then don't vote Conservative, vote Ukip and make sure there are enough Ukip MPs in Westminster to hold Mr Cameron to that pledge to make that referendum happen this year - only Ukip MPs will be able to hold Mr Cameron's feet to the fire and that is what we intend to do after May 7."

"If you want a referendum to happen and for there to be a free and fair vote, then return Mark [to Westminster]."

On immigration, Mr Farage used the rally to underline that the party was the only one to be trusted to tackle the problem.

"What Ukip is saying is 'let's be positive about the Europe but let's get back our controls so we can control the quality of people who come to the UK'."

He also downplayed polls showing Ukip support slipping, claiming that they under-estimated the level of support the party was getting.

"Up to one in three people who are saying they are going to vote for me did not vote in 2010 and in many cases have not voted in their lives before."

He stood by his controversial remarks on health tourism, saying that treating foreign nationals was depriving UK patients of treatment.

Earlier, Mr Farage - surrounded by the now familiar presence of a large group of camera crews and reporters - staged a walkabout in the high street and stopped off at Tiny Tims cafe for a cup of tea.

Mr Reckless told the audience that he was making the NHS a major priority in his campaign.

He cited a voter who had come to him saying they had been unable to get a routine GPp appointment for six weeks.

"That is unacceptable. I was brought up in the NHS - my parents met working in the NHS and it is an expression of our patriotism. It is something that brings us together as a country and a system of mutual assurance."

Mr Reckless is facing a stiff challenge in the seat he won just six months ago when he triggered a by-election after defecting to Ukip and won with a majority of 3,000.

The Conservatives believe they can recapture the seat saying that the defeat in November was largely down to a protest vote.