Key Points:

Borat you're banned.

That's the message from Wellington police who say they will not allow rugby fans to wear the skimpy swimsuit of movie star Borat at a rugby sevens tournament in the city this weekend.

The sevens is one of the highlights of the Wellington social calendar and those who do not dress up are among the minority, but police are warning people to be careful when choosing their outfit.

Last year police turned a blind eye when dozens of men turned up in the revealing figure-hugging yellow swimsuits Sacha Baron Cohen made famous in his hit movie Borat.

They will be turned away this year, Inspector Kevin Riordan told TV3 on Sunday.

"It's a family event and there will be children there," he said, appealing to fans to have "a sense of decency".

Last year about 100 people were kicked out of the stadium and 25 people arrested.

"We do want fans to enjoy themselves, but to do so safely and without causing problems for others," Mr Riordan said.

"We encourage people to drink plenty of water, to moderate their alcohol intake and to look after their mates."

"Take your friends home or back to their hotel if they have had too much to drink, otherwise they could be spending the night at our place," he said.

Police had been working closely with stadium, rugby union and city council officials to ensure that the event was enjoyable for everyone.

Steps being taken include:

* A public liquor ban running from 5pm to 8am on both Friday and Saturday during the event;

* security officers searching bags to ensure alcohol isn't carried into Westpac Stadium;

* issuing two-year trespass orders from the stadium to anyone caught smuggling alcohol into the event;

* enforcing a stadium dress code which includes leaving weapons such as imitation swords or firearms at home; and

* closing Courtenay Place between Taranaki Street and Cambridge Terrace to traffic on Saturday night to create a pedestrian only zone.

Mr Riordan said about 100 police were working on the police operation for the sevens, including drafting in some extra staff from Hawke's Bay, Gisborne and Palmerston North.