While the Conservatives still enjoy a commanding lead Labour were up two points on 32 per cent, with the Tories down one on 45, a YouGov poll for The Times found.
The Liberal Democrats saw support plunge three points, with eight per cent, while Ukip were up one on six per cent.
Data were gathered as Labour’s manifesto launch, which included a raft of spending plans as well as tax hikes for the rich and corporations, was dominating the news agenda on Tuesday and Wednesday.
The boost for Mr Corbyn’s party comes amid a gradual rise in Labour’s polling numbers since the start of the campaign.
Some Labour moderates fear that Mr Corbyn could use the findings as a way of clinging to power even if the party loses the election.
Mr Corbyn’s allies believe he is likely to be able to stay in office should he win more than the 30.4 per cent share of the vote which Ed Miliband achieved in the 2015 election.
YouGov’s Anthony Wells told The Times: “Labour seem to be holding up because they’re still getting the votes of a substantial chunk of people who don’t like Corbyn and are presumably holding their noses and voting Labour anyway.”
The polls show Labour is more trusted by voters on the NHS, education and housing, while the Conservatives are preferred on issues including the economy, immigration , law and tax.
General Election polls and projections: May 17
Unite union boss Len McCluskey, a backer of Mr Corbyn, said earlier this week that winning just 200 seats would be a good result for Labour, adding: “I don’t see Labour winning”.
The party won 232 seats in the 2015 election.