LONDON (AP) _ Princess Diana and her future sister-in-law were mistaken for ''kiss-o- gram'' girls at a London nightclub when they arrived wearing police uniforms they had planned to use to crash Prince Andrew's bachelor party.

Lewis Louis, the manager of Annabel's nightclub, said four women in high spirits arrived dressed as policewomen, but no one recognized the princess or Andrew's bride-to-be, Sarah Ferguson.

''For a moment it must have seemed like a police raid, then guests obviously decided they were 'kiss-o-gram' girls. One of the staff told them that one or even two 'kiss-o-gram' girls might be all right but four of them was a bit of an embarrassment to others.

''One of the four apologized for the fact that there were so many of them and promised, 'We'll be leaving soon','' he said. ''They were perfectly disguised and certainly had us fooled.''

Diana, the 26-year-old Miss Ferguson and two other young women walked into Annabel's early Wednesday after shelving a plan to barge into Andrew's party, news reports said.

Princess Diana, 25-year-old wife of the heir to the British throne, told guests at a Buckingham Palace garden party Thursday about her night on the town with Miss Ferguson, who will marry Prince Andrew next Wednesday.

''It was so hot in the wig and my feet were killing me - the shoes were two sizes too small,'' the British Broadcasting Corp. quoted Diana as telling one guest.

Newspapers quoted regulars at Annabel's, including a society hostess and the treasurer of the governing Conservative Party, as saying the four sat in a corner giggling and sipping champagne.

All four women wore black uniforms, with peaked policewomen's hats, rented from a theatrical costume company. Miss Ferguson wore a short brown wig and Diana wore glasses and a black wig.

''There is an offense of impersonating a police officer - but they were supposed to be in fancy dress,'' said a Scotland Yard spokeswoman, who by custom was not named.

Press Association, Britain's domestic news agency, said the practical joke was set up by comedian Pamela Stephenson, whose boyfriend, Scottish comedian Billy Connolly, was a guest at Andrew's stag party early Wednesday morning.

But the agency said the princess and the bride-to-be apparently got a case of nerves and went to Annabel's instead of the party, with Miss Stephenson also masquerading as a policewoman. The fourth woman was not identified.