Campaigners in the UK are reminding Irish people based in Britain that midnight tonight is the deadline for registering to vote in the upcoming Brexit referendum.

All that is required to register is an Irish passport or national UK insurance number.

Members of the Irish Government - including Minister for Foreign Affairs Charlie Flanagan and Taoiseach Enda Kenny - have visited the UK to urge Irish emigrants living there to vote to remain in the EU.

David D'Arcy, a spokesperson for the 'Irish4Europe' campaign, said: "If the Leave campaign are successful in their objectives, then we're looking at an exit from the customs arrangement that we have. We're also looking at the heightening of migration controls at the border...

"We do have a Common Travel Area, [but it] only applies to UK and Irish citizens."

Meanwhile, Minister Flanagan has warned of a "divorce of unprecedented complexity" in the event of a Brexit:

Bob Geldof is also encouraging Irish people to register ahead of the deadline.

Bob Geldof has a message you need to make sure your friends see before tomorrow. WATCH: https://t.co/FoiUTSKVKs pic.twitter.com/o5b64wiZdO

— Irish4Europe (@Irish4Europe) June 6, 2016

Earlier, British Chancellor George Osborne warned that a British vote to leave the EU would cost the Northern Irish economy £1.3bn (€1.65bn).

However, Northern Ireland's First Minister, Arlene Foster, is campaigning in favour of British withdrawal.

You can find out more details about the registration process on the Irish4Europe website.