The Angus Reid Public Opinion poll showed the Conservatives on 39 percent of the vote, unchanged from its previous survey last week, with Labour steady on 26 percent and the opposition Liberal Democrats up 3 points on 21 percent.

If the findings were repeated uniformly across the country at the election, widely expected on May 6, the Conservatives would have a small majority of around 30 in a 650-seat parliament, according to a poll predictor on the Sky News website.

Canadian pollster Angus Reid uses different assumptions from other polling firms and has regularly found a larger lead for the Conservatives than reported in other surveys.

Other pollsters have shown the Conservative lead shrinking since mid-January to below the 10-point gap regarded as necessary for the party to be sure of a majority in parliament.

Angus Reid says its sampling methods account for around 3 percentage points of the lower reading it gives Labour compared to other pollsters.

Its online panel of respondents also gives greater backing to right-wing fringe parties than found by telephone-based pollsters, perhaps because of the relative anonymity of the Internet.

Labour needs a smaller percentage of the national vote than the Conservatives to win an overall parliamentary majority because its vote is concentrated in urban constituencies, which tend to have smaller electorates than rural areas.

As a result it would be possible for the Conservatives to win a greater share of the national vote but still win fewer seats than Labour.

Angus Reid polled 2,003 adults online on March 15 and 16.