Bags of more than three litres in capacity will not be allowed into the annual beer celebration, which runs from September 17 to October 3, deputy mayor Josef Schmid said.

The Oktoberfest "won't become a high-security zone, but there will be important changes that affect all guests", Mr Schmid told reporters.

Security staff will also be strengthened.

Mr Schmid said officials had already planned to raise the number of security guards from last year's 250 to 350. That number will now be upped to as many as 450 at peak times.

A 350-metre fence will be put up to secure a previously open entrance to the festival grounds, Mr Schmid said.

Bavaria was shaken last month by three attacks in a week.

Two were carried out by asylum seekers and claimed by Islamic State. Only the attackers were killed.

In an unrelated attack, a teenager killed nine people and then himself in a shooting rampage in Munich.

The new security measures followed a review over recent weeks.

Mr Schmid stressed that there is "no concrete danger" to the Oktoberfest - "there are no threatening videos or anything like that".