Ballot papers are being dispatched to around 647,000 eligible voters in the Labour leadership election.

Over half of those able to vote in the contest are party members; a further 129,000 people who paid £25 each to be registered as supporters also have a vote, as do 168,000 people who are members of affiliated trade unions and other organisations.

Those eligible can cast their vote by post or online.

Labour's National Executive Committee (NEC) banned members who joined the party in the last six months from taking part in the contest.

If they wished to vote in the election they had to register as a supporter and pay the £25 fee in addition to their monthly membership fees.

Five party members took the NEC to the High Court to contest the decision.

The High Court judged the ban to be"unlawful" as it was a breach of contract between the members and the party.

That decision was overturned at the Court of Appeal, however, and the ban was reinstated.

The contest was triggered shortly after 172 of the party's MPs expressed no confidence in Jeremy Corbyn's leadership.

Only 40 MPs expressed confidence in his leadership.

Following Angela Eagle's decision not to run in the contest, Welsh MP Owen Smith is Corbyn's sole challenger.

Voting will close at midday on September 21.

The result will be declared at a special party conference on September 24 in Liverpool.

It is the first two candidate Labour leadership contest since John Smith and Bryan Gould battled for control of the party in 1992.

A hustings will take place between Corbyn and Smith in Glasgow on Thursday.