Gardaí are investigating what they believe was a "credible threat" to the Intel plant in Leixlip, Co Kildare.

The alarm was raised shortly after 6am this morning, and staff were evacuated from the building - which employs around 4,000 people.

The alert ended without incident and the company said its employees returned to work.

A spokesperson for the Defence Forces said earlier the operation was led by the gardaí, and the army bomb disposal squad was not deployed to the area.

"As per normal protocol, gardaí shortly thereafter coordinated a response with Intel. A controlled evacuation of the site followed and a search was conducted by trained Intel security personnel throughout the campus with the buildings being declared safe just after 8.30am," Intel said in a statement.

There had been traffic diversions in place, but these were lifted after the alert ended.

While Dublin Bus say its route 66/66x - which was diverted inbound from Tesco in Maynooth to Leixlip onto the N4 - was also restored.