Two Cambodians were killed and 12 others, including a Portuguese tour guide and an Indian medical officer on United Nations duty, were wounded. An Australian soldier fired back, only the second time UN peace-keepers in Cambodia have done so, but apparently did not hit anyone.
The town is the base for tourists visiting the nearby Angkor Wat temple complex, the crowning monument of the 12th-century Khmer empire. A French embassy spokesman in Phnom Penh said that despite the attack Mr Mitterrand would go ahead with a visit tomorrow to Angkor Wat and a French Foreign Legion engineering detachment stationed in Siem Reap.
The UN Transitional Authority in Cambodia (Untac) said the gunmen wore a mixture of uniforms, and that it was not possible to apportion responsibility for the attack. The Phnom Penh government immediately blamed the Khmer Rouge, which condemned Mr Mitterrand's visit to Cambodia in a radio broadcast as a violation of international law. But the location and timing of the attack are suspect: despite the struggle for control between the two factions in the north of Siem Reap province, the capital is normally regarded as being firmly under government control. After the gunmen withdrew, government forces patrolled the area in armoured personnel carriers.
Untac has been unable to quell violence in many rural areas of Cambodia, but yesterday's rampage in one of the country's larger and more tranquil towns has no precedent since its peace-keeping mission began. Many new hotels and restaurants have opened up along Siem Reap's tree-lined streets to accommodate UN personnel and the influx of tourists, reassured by Untac's presence, who come to visit Angkor Wat. The attack took place near the French forces' quarters and the recently-renovated Grand Hotel, built in French colonial days, which was full of tour groups. One of their guides was wounded when he looked out of the window of his room.
Apart from accusing the Khmer Rouge, Phnom Penh will be able to use the incident to discredit the UN authority, which it regards with suspicion. It is expected to fare poorly in the UN-organised election in May.
Mr Mitterrand arrives in Phnom Penh today from Vietnam, where he urged the United States to lift its economic embargo, but also called on the country's Communist leaders to allow more political freedom. Yesterday he visited Dien Bien Phu, where French forces surrendered to Vietnamese insurgents in 1954 - a historic defeat which brought to an end more than a century of French involvement in Indo-China.