Updated | UK elections: Labour a point ahead in final pre-election poll

Labour has moved into a wafer-thin one-point lead, according to the the final pre-election Guardian/ICM poll, leaving the country on a knife-edge with the markets starting to jitter.

On Wednesday, ICM released provisional numbers which showed the two main parties deadlocked on 35% each. But the telephone fieldwork continued into evening, and the final figures – based on the full sample of 2,000 interviews – find Labour holding steady on 35%, while the Conservatives slip to 34%.

An 11% share for Ukip, 9% for the Lib Dems and 5% for the Scottish Nationalists are all confirmed from the provisional poll, but in the final tranche of interviews the Greens picked up a point, climbing from 3% to 4%. The difference is still within the margin of error, but every poll is now indicating a hung parliament and the tightest election in decades.

Millions of people will be casting their votes in the UK general election today. Polls opened at 07:00 local time at around 50,000 polling stations across the country.

A total of 650 Westminster MPs will be elected, with about 50 million people registered to vote. As well as the general election, there are more than 9,000 council seats being contested across 279 English local authorities.

Mayors will also be elected in Bedford, Copeland, Leicester, Mansfield, Middlesbrough and Torbay.

Some votes have already been cast, through postal voting, which accounted for 15% of the total electorate at the 2010 general election, when the overall turnout was 65%. For the first time, people have been able to register to vote online.

Most polling stations are in schools, community centres and parish halls, but pubs, a launderette and a school bus will also be used.

PM David Cameron

Ed Miliband at the polling station

UKIP's Nigel Farage

Green Party leader Natalie Bennet

The SNP's Nicola Sturgeon

A handful of seats are expected to be declared by midnight, with the final results expected on Friday afternoon.

PM David Cameron, UKIP leader Nigel Farage, SNP's Nicola Sturgeon, Green Party leader Natalie Bennet and Labour's Ed Miliband have already cast their votes.