The hall was bedecked with Lindh's favourite flowers

The British, French, German and Greek foreign ministers were among the mourners, who included the President of the European Commission, Romano Prodi, former chief UN weapons inspector Hans Blix and Swedish King Carl Gustaf XVI.

Swedish police mounted the biggest security operation in the capital for nearly 20 years, with snipers positioned on rooftops overlooking City Hall and private flights banned over the city centre.

A Swedish prosecutor, meanwhile, has asked a court for more time to question a suspect in connection with the killing of Lindh, who was stabbed in a Stockholm department store last week.

'Warmth and joy'

The red-bricked City Hall, venue of Nobel prize award banquets, was bedecked with blue delphinium flowers - Lindh's favourite colour - and white floral sprays and candles as the Stockholm Chamber Orchestra and Los Angeles Philharmonic Orchestra played classical music.

We'll carry the memory of Anna with us for a long time Goran Persson, Swedish prime minister In pictures: Memorial service Persson's tribute

Anna Lindh's favourite singer, Eva Dahlgren, opened the service with a performance of An Angel in the Room.

Standing in front of a large picture of a smiling Anna Lindh, Swedish Prime Minister Goran Persson paid an emotional tribute to his former cabinet colleague.

"We have lost her, this is so, and this awareness hurts so dreadfully," he told the mourners.

"We'll carry the memory of Anna with us for a long time... she was a source of warmth and joy," he said.

Security blanket

As the service took place, streets around City Hall were closed off and traffic was barred from the canal beside the building.

Anna Lindh: Life in pictures Press portrait of suspect

Police spokesman Lars Groenskog said the city was deploying "the biggest security force since the funeral of Olof Palme", Sweden's prime minister who was murdered in 1986.

About 1,300 guests were invited to the service, organised by Lindh's family and her Social Democratic Party.

US Secretary of State Colin Powell had been due to attend, but was forced to cancel because of the extreme weather caused by Hurricane Isabel.

The service was broadcast live on television in Sweden, Denmark, Finland and Norway.

Lindh will be buried at a separate private ceremony on Saturday.

Court request

Police investigating the Lindh's murder are continuing to hold a man arrested on Tuesday.

Anita Andreasson, a Stockholm district court spokeswoman, said: "We have received a request to remand him in custody because there are reasonable grounds to suspect him of the murder."

She said the court would review the request later on Friday, Reuters news agency reported.

Swedish police have received the results of a DNA test that should show whether a 35-year-old man held over Lindh's killing had been wearing a baseball cap found near the crime scene.