Dozens of Spitfire fighter planes that were buried by British troops in Burma as the second world war drew to a close are to be excavated after an agreement to dig up the historic aircraft was signed by the Burmese government and an aviation enthusiast from Lincolnshire.

After 16 years of searching and lobbying, David Cundall, 62, has signed a deal to recover the lost RAF planes, which are believed to have been packed in crates and hidden by British forces on the orders of Earl Mountbatten shortly before the United States bombed the Japanese city of Hiroshima on 6 August 1945.

During his visit to Burma in April, David Cameron reached an agreement with President Thein Sein about the recovery of the missing aircraft. The British embassy in Rangoon said the newly signed deal was a chance to work with the new Burmese government "in uncovering, restoring, displaying these fighter planes".

Excavation work is expected to begin by the end of this month. The number of Mark 14 Spitfires awaiting discovery remains unclear, but Htoo Htoo Zaw, managing director of Cundall's Burmese partner, the Shwe Taung Paw company, said he estimated there were at least 60. Previous estimates have varied between 20 and 36. Even that number would represent a large increase in the global Spitfire population: while 21,000 were built, only 35 remain in a good enough condition to fly.

"This will be the largest number of Spitfires in the world," Htoo Htoo told the Associated Press. "We want to let people see those historic fighters, and the excavation of these fighter planes will further strengthen relations between Myanmar [Burma] and Britain."

A local newspaper, Myanmar Ahlin, reported that the excavation agreement was signed by Cundall on behalf of his British company DJC, Tin Naing Tun, the Burmese director general of civil aviation, and Htoo Htoo.

For Cundall, it is a triumphant end to years of hunting for the fighters. He says he has spent £160,000 trying to locate the lost treasure, vying with potential rivals for the deal.

In April, he claimed he had secured financial backing for the planes' excavation from an anonymous investor, and in August told the Birmingham Post he wanted to see the aircraft return to the UK. "Spitfires are beautiful aeroplanes and should not be rotting away in a foreign land," he was quoted as saying. "They saved our neck in the Battle of Britain and they should be preserved."

A Downing Street spokesperson said: "We are pleased to hear that contracts have been awarded, which mean that the digging up of the Spitfires in Burma can begin. We've always said that we want to see these Spitfires back home in Britain – perhaps one day even flying over the skies of Britain – and today's news brings us another step closer to that."