250,000 One Direction fans on way to Dublin

More than a quarter of a million One Direction fans will descend on Dublin this weekend for their three nights in Croke Park.

A massive security operation swings into force later this afternoon with concert-goers being warned that they will not be able to queue up outside the venue until gates open.

The boyband take to the stage at 8.30pm tonight. The gig is due to end at around 10.15pm.

Superintendent Kevin Galtron from Mountjoy garda station urged fans to take public transport.

"We've extra trains from Drumcondra station (and) Connolly station has additional Luas trams coming in," he said.

"There are extra DARTs too (and) additional train services up to midnight going almost to the four corners of the country."