There will be a strong Garda presence at tomorrow's Eminem gig at Slane Caste checking for alcohol and drugs. Oh and don't bring any umbrellas.

Overall 750 Gardai will be on duty according to the officer in charge of the massive security operation which begins this afternoon and ends on Sunday morning.

Superintendent Michael Devine also warned concert-goers about searches for "alcohol and offensive weapons."

Speaking on Morning Ireland this morning, Devine said that there will be a strong Garda presence in preparation for the 80,000 fans who are expected to descend on the Slane venue.

Gates open at 12 noon for the show and Devine urged fans not to arrive with "significant amounts of alcohol or in an intoxicated state."

"In the past we've had private buses which have arrived with slabs of beverages and not just one and we will not be entertaining that," he said. "In fact we will not be entertaining any significant amounts of alcohol at all. It's not fair on other patrons and it's not fair to the residents of Slane so we will be adopting a robust approach to that type of activity."

Devine added that Gardaí will be carrying out searches for "illegal substances and offensive weapons" at the concert and that fans are advised not to bring umbrellas into the concert area.

"Umbrellas would be of a light nature compared to what one would be looking for," he said. "However we would advise against umbrellas because some people in the past have used them for other purporses rather than what they were designed for so we will not be allowing them into the venue."

Asked if the "nature" of Eminem's music will make Gardai extra vigilant tomorrow, Devine said, "I suppose it's different from anything that has appeared at Slane. However, we've had full houses here before so the numbers are no different yes, you would have a different type of patron at this event.

"I suppose they would have a different musical interest, probably more robust in their approach to the activities that go with the music so things can get a little bit awkward."

Eminem, who turns 40 later this year, is playing Slane eight years after he cancelled a scheduled concert at the venue because he was "tired."