Image copyright EPA Image caption Director Ken Loach is a member of the Left Unity party

About 1,200 people have been banned from voting in Labour's leadership contest because they support rival parties.

Labour said the number would rise as officials check the credentials of new members hoping to take part.

The party says those blocked included film director Ken Loach, journalist Toby Young and Tory MP Tim Loughton.

Mr Loach hit back at Labour's claim he had been prevented from taking part in the leadership election.

The film director quit the Labour Party some years ago over its "drift to the right" and is now a member of Left Unity, a left wing group formed last year.

'Small print'

He believed he was entitled to a vote in Labour's leadership contest as a union member - but Labour's rules have changed recently so that trade unionists have to register as "affiliated supporters".

Mr Loach said he did this but then decided not vote after reading the "small print" - voters have to sign up to Labour's aims and values.

Mr Loach told BBC News: "I do not support the politics of the current leadership in the Labour Party and Left Unity was founded to uphold the interests of working class people, the very values that Labour had abandoned".

People have until noon on Wednesday to apply to take part as a member or supporter, with the first ballot papers sent out on Friday.

Labour says it has a "robust system to prevent fraudulent or malicious applications" after claims that Conservatives and members of "hard left" groups were signing up in order to back left wing candidate Jeremy Corbyn.

Among the 1,200 were 214 people from the Green Party, 37 from the Trade Unionist and Socialist Coalition, 13 Tories, seven from UKIP and one from the BNP.

Also thought to have been blocked from voting were:

A former Liberal Democrat MEP

Green Party members spotted discussing on Facebook how to get around the system

A Conservative candidate who was spotted by a membership secretary

Labour said verification checks would continue even once votes had been cast.

Labour leadership contest

Image copyright Getty Images Image caption Labour leadership candidates (l-r): Liz Kendall, Andy Burnham, Yvette Cooper, Jeremy Corbyn

Who are the candidates? Andy Burnham, Yvette Cooper, Jeremy Corbyn, Liz Kendall

Andy Burnham, Yvette Cooper, Jeremy Corbyn, Liz Kendall Dates: Ballot papers will be sent out on 14 August; voting can take place by post or online. They must be returned by 10 September. The result is announced on 12 September

Ballot papers will be sent out on 14 August; voting can take place by post or online. They must be returned by 10 September. The result is announced on 12 September Who can vote? All party members, registered supporters and affiliated supporters - including those joining via a union

All party members, registered supporters and affiliated supporters - including those joining via a union What is the voting system? The Alternative Vote system is being used so voters are asked to rank candidates in order of preference

The Alternative Vote system is being used so voters are asked to rank candidates in order of preference How does it work? If no candidate gets 50% of all votes cast, the candidate in fourth place is eliminated. Their second preference votes are then redistributed among the remaining three. If there is still no winner, the third place candidate is eliminated with their second preferences (or third in the case of votes transferred from the fourth place candidates) redistributed. It is then a head-to-head between the last two candidates

At-a-glance profiles of the four contenders

The latest figures show Labour's membership is 282,000 - an increase of more than 80,000 since the general election defeat.

This includes 70,000 registered supporters, who are able to take part in the vote for a £3 fee if they agree they "support the aims and values of the Labour Party".

The party has 48 members of staff working at a call centre in Newcastle, sifting through applications.

Acting leader Harriet Harman has also written to local Labour parties and MPs, asking them to check for suspicious names.

Mr Loach, whose left wing party fielded 10 candidates at the general election, said: "I did not apply to join the party. I make political contributions through my affiliated union and assumed that that gave me the right to vote."

A Labour spokesman said: "The party has an absolute focus on ensuring that the rules agreed in 2014 for electing the new party leadership are complied with and the integrity of the process is upheld."