The head of American troops in Afghanistan, General Dan McNeil, has promised a thorough investigation into an incident in which civilians were killed by US bombs in Uruzgan province.

Certainly, the president expressed to President Karzai that this was a tragic loss

White House spokesman

At a joint press conference in Kabul, Afghan Foreign Minister Abdullah Abdullah said 48 people were killed and 117 injured when US planes bombed a wedding party on Monday.

Both men denied they were time-wasting because of the embarrassing political implications of the bombing.

After a joint US-Afghan team returned from the area, General McNeil told reporters: "We have determined there were civilian casualties."

But he indicated that not all the civilians may have been innocent.

"We will initiate all formal investigations to determine what caused these civilian casualties and what we can do or implement to make sure they do not recur."

The Pentagon has maintained that the US planes came under hostile fire.

However, General McNeil said the investigating team did not find any anti-aircraft guns in the area.

He said the inquiry would probably take a few weeks to complete.

But he insisted that there would be no attempt to sweep the matter under the rug.

The BBC's Kate Clark in Kabul says the incident has left Afghans angry and perplexed.

She says these are difficult times for the Afghan Government with its closest ally accused at the very least of being careless with Afghan lives.

No apology

On Friday, US President George W Bush telephoned the Afghan leader, Hamid Karzai, to express his sympathy for the loss of life in Monday's bombing raids by US warplanes.

Mr Bush spoke to President Karzai for about five minutes, describing the death of Afghan civilians as a tragic loss and passing on his sympathies to the families of those who died.

Sorrowing Afghans are wondering about US actions

The word 'apology' has not been used in Washington because for now there remain differing accounts of what happened on Monday morning.

The Americans insist their planes were simply responding to anti-aircraft fire from the ground - much more intense than the scattered gunfire which by tradition follows Afghan weddings.

Both Mr Bush and Mr Karzai have restated their commitment to finding any al-Qaeda fighters who may be hiding in the area.

But the incident has done little for America's public relations in Uruzgan.

The governor of the province has warned of a holy war against the United States if more civilians are killed.