The war in Kosovo cost more than £30bn, a joint study by the BBC and military experts has found.

In what is believed to be the most comprehensive study of the war to date, the BBC team working with Jane's Defence Weekly found that the first day of bombing alone cost more than £44m as Nato warplanes struck targets throughout Yugoslavia.

The study, part of a BBC series, Kosovo: The Reckoning, found that while the costs of waging war against the Serbian military machine were massive, the bill for rebuilding the shattered Balkans will be far higher.

The BBC/Jane's research does not include the costs of environmental damage following bombing raids on oil refineries and industry.

According to the study, two-thirds of the estimated costs will eventually go on rebuilding the region - seven times more than the £2.5bn spent during the 78 days of bombing operations.

During the conflict, Nato:

• Dropped more than 23,000 bombs and missiles
• Spent more than £150m on fuel in the first week
• Destroyed almost half Yugoslavia's industrial production
• Caused £1.74bn damage to the Yugoslav economy, according to Serbian experts

Military costs

One of the most significant costs borne by Nato was the loss of a £56m US stealth fighter, downed in uncertain circumstances during the first week.

But while the costs mounted, General Wesley Clark, head of Nato in Europe, told the BBC that the alliance had been prepared for whatever was needed to end the ethnic cleansing in Kosovo.

"We never set a standard for ourselves to stop it in two days, four days eight days, 10 days," Gen Clark said.

"When we wrote the plan we knew that there would be many circumstances around the event that would make those kinds of predictions impossible."

Anthony Cordesman, a military analyst at the Pentagon, the home of the US forces, said that the operation to identify and approve targets had been huge.

"You had thousands of people searching for targets and trying to estimate and, in many cases, guess what a given strike would actually do to influence Serbian behaviour," he said.

"Sometimes they'd simply attack by numbers. They knew there was a category and they kept hitting it. In others they experimented."

And while the targeting operation led to major civilian disasters, including when Nato struck both trains and a refugee convoy, one analyst said that the much-vaunted smart weapons were almost as impressive as the hype.

Nick Cook, aviation editor of Jane's Defence Weekly, said: "The weapons pretty much performed as advertised.

"There were some bad collateral hits on civilian targets, but as a war of such immense scope and breadth, it was inevitable that there was going to be some civilian targets hit, no matter how accurate the weapons were."

Economic toll

But, the documentary finds, the costs of the region recovering from the war will be greater still.

An estimated 500,000 landmines, produced before the war in Yugoslavia itself, are buried throughout Kosovo.

Experts estimate there could also be as many as 10,000 unexploded munitions which ultimately will have to be defused by Nato peacekeepers.

Economic experts now believe that Yugoslavia has replaced Albania as Europe's poorest nation.

At least 30% of the adult population is unemployed.

The economic collapse was caused as Nato switched to hitting infrastructure targets as the war continued.

According to figures from the Danube Commission and others, the cost of replacing all eight bombed bridges over the vital river will be at least £80m - perhaps up to ten times more than the cost of destroying them.

The closure of the bridges is costing the Balkans around £600m a year - and Romania says it has lost at least £580m this year alone.

Srboljub Antic, a Yugoslav economist, said: "Due to Nato's intervention, Serbia lost 40% of its gross domestic product. We also lost 44% of our industrial production.

''We now have at least 250,000 people unemployed with this intervention and the whole social situation is a real disaster.

"If we rely on our resources we will need 40 to 80 years to recover," he stressed.