Munich (dpa) - Tens of thousands of people stormed the Oktoberfest beer festival grounds on Saturday after organizers opened the gates in the German city of Munich.

Despite official warnings not to run on the premises - announced via loudspeakers in English, German and Bavarian dialect - visitors sped through the gates to secure their seats in the beer tents.

They will have to way a few more hours to get their hands on a beer, however. Munich's Mayor Dieter Reiter will mark the festival's opening by hitting the first barrel of beer with a large mallet at noon (1000 GMT).

Around one hour ahead of the official opening, several tents had already closed their doors due to overcrowding. Even those on the tents' guest lists were not being admitted, organizers said.

Earlier this week, Reiter emphasized the importance of ensuring a safe and peaceful "Wiesn," as the festival is known locally.

"I have a good feeling," he said in comments during his official tour of the preparations.

Fewer Munich residents than usual had approached him with concerns ahead of the event, Reiter said. "That's a good omen," he commented.

Good weather was expected for the opening ceremony, where Reiter will bellow the traditional cry, "O'Zapt is," announcing the breaching of the barrel and the start of the 186th edition of the festivities.

According to the official website, the six beers on offer "must be brewed with Munich water from a deep well and have an original wort content of at least 13.6 per cent, which makes them stronger than normal light beer."

Booking ahead of the world's premier beer festival was reported to be strong, with predictions that the 6.3 million visitors recorded last year could be exceeded.

"It doesn't have to be a record year," Oktoberfest head Clemens Baumgaertner said, as long it is a "quality Wiesn."

The festival finishes on October 6.