UK PM May's lead over Labour shrinks

With less than a week to go before the British election, a poll shows the Conservatives' share of the vote has fallen to 45 per cent.

British PM Theresa May's lead over the opposition Labour party has shrunk to five points. (AAP)

British Prime Minister Theresa May's lead over the opposition Labour party has shrunk to five points from 15 points just over two weeks ago, an opinion poll from Ipsos MORI shows.

With less than a week to go before the national election, the poll showed the Conservatives' share of the vote had fallen to 45 per cent, down four percentage points since the previous poll published on May 18.

Labour's share of the vote increased six points to 40 per cent, according to the poll which was published by the London Evening Standard newspaper.

The poll is the latest to show a narrowing lead for May. A YouGov opinion poll on Wednesday showed the Conservatives' lead had fallen to a fresh low of 3 points.

A failure to win the election with a large majority would weaken May just as formal Brexit talks are due to begin, while the loss of her majority in parliament would pitch British politics into turmoil.