Factbox: A United Kingdom divided over Brexit: early results of the EU election

LONDON (Reuters) - Nigel Farage's Brexit Party was set to sweep to victory in the European election, with both Prime Minister Theresa May's Conservatives and the opposition Labour Party losing support across the country, early results showed.

For a menu of stories on the EU election:

WHAT DO THE PRELIMINARY RESULTS SHOW？

Nigel Farage's Brexit Party is on course to win while smaller pro-European Union parties are also gaining. Both the Conservatives and Labour are losing support. A BBC projection put the pro-EU Liberal Democrats on second place.

WHO GETS ELECTED？

The United Kingdom is divided into 12 electoral regions - nine in England, and one each for Scotland, Wales and Northern Ireland. In total it will elect 73 MEPs (Members of the European Parliament).

WHAT SYSTEM IS USED？

In Britain, parties submit a list of candidates for each region and voters select a party rather than an individual candidate, unless they are backing an independent.

As the seats are allocated to a party, they in turn allocate them to candidates starting from the top of their list.

In Northern Ireland, as votes are counted the candidate with the least votes in eliminated and their votes redistributed. This is repeated until there are only the required number of candidates left for the number of seats available.

ISN'T THE UK LEAVING THE EU？

Britain is taking part in the elections because it delayed the date of its exit from the EU, but its MEPs will leave the parliament when Brexit happens.

WHAT WERE THE RESULTS IN 2014？

Turnout: 35.6 percent

Sources: UK Electoral Commission, European Parliament, regional election officials