KEY marginal seats in and around Bradford will "heavily influence" who walks through Number 10 on polling day, according to bookmakers.

And betting is hotting up in three particular constituencies where the results are expected to be very close - Bradford West, Keighley and Pudsey.

Labour is poised to wrestle control of Keighley back from the Conservatives, and could also take Pudsey and Bradford West, according to spread betting firm Sporting Index.

In Keighley, Conservative Government minister Kris Hopkins is defending a majority of nearly 3,000 votes but Labour candidate John Grogan is now favourite to retake a seat that could be critical for the party's aspirations in Westminster.

The race to win Pudsey is neck and neck, with sitting Tory Stuart Andrew defending a majority of just 1,659 votes. Labour is mounting a fierce challenge through candidate Jamie Hanley, and Sporting Index makes it too close to call. Pudsey is 26th on Labour’s target seats list.

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In Bradford West, the contest between Respect and Labour is also very close, according to the firm.

Respect leader George Galloway, elected in a 2012 by-election with a majority of more than 10,000 votes, is favourite to win but Labour's Naz Shah is not far behind.

Ed Fulton, political spokesman for Sporting Index, said: "Seats in and around Bradford will heavily influence who walks through Number 10 after polling day.

"Labour do look like taking Keighley and could yet add Pudsey into their column as well - and it doesn’t look like George Galloway is safe yet either. "However, there is still a long way to go until May 7 and there will certainly be twists and turns in the road ahead for all candidates.

"As quickly as fortunes can change for politicians, so do the markets. It’s still all to play for."

The firm doesn't yet offer bets on the constituencies of Bradford East, Bradford South or Shipley - though these could be added at a later date.

Mr Fulton said in the 2010 General Election, Sporting Index's predictions proved "closer than any opinion poll".

He said: "With such tight races in and around the Bradford area, we’re expecting West Yorkshire voters with on the ground knowledge to challenge our predictions."

Rival spread-betting firm Spreadex is also offering bets on Bradford West, listing it as one of its 100 key marginals.

It too has Mr Galloway ahead of Ms Shah by a whisker.

Spreadex spokesman Andy MacKenzie said: "The indications from our traders are that this is one of the most tightly-contested elections for many years and the outcome of the Bradford West constituency could be key to the overall result."

Spread betting is a high-risk form of gambling in which people try to predict not just who will win or lose a contest, but by how much.