In the pre-dawn hours of July 22, 1974, a transport plane full of Greek commandos on a secret mission to Cyprus was shot down by friendly fire.

For more than 40 years, the exact whereabouts of the remains of 19 of the soldiers -- sent to support Greek Cypriot forces against invading Turkish troops -- has been a mystery.

But now efforts are underway at a Nicosia military cemetery to unearth the remains and finally send them home, digging up an ugly past that has haunted the soldiers' families and ties between Greece and Cyprus.

Due to its embarrassing circumstances –- Greek Cypriots shooting down Greek comrades -- the incident has been largely brushed over in the aftermath of the war in Cyprus.

"It was shot down by friendly fire and it crashed, and under instructions of the army, they buried it... it was an embarrassment," human rights lawyer Achilleas Demetriades told AFP.

"It is unacceptable that it took so long to dig up a known grave to deliver remains to the loved ones," he said.

In fact, the move comes only after the families of two Greek army officers who died in the incident brought a case to the European Court of Human Rights. This prompted the government to dig up the transport.

The aircraft -- the Noratlas -- was part of a secret mission codenamed Operation Niki (Victory) to airlift a commando battalion from Greece to help the Greek Cypriot National Guard fend off the better-equipped and much larger Turkish army.

- Mistaken as hostile -

Turkey invaded the northern part of Cyprus on July 20, 1974 in response to a coup orchestrated by the Greek military to unite the Mediterranean island with Greece. It remains split into a Turkish-held north and Greek Cypriot south.

Thirteen aircraft were dispatched from the Greek island of Crete with commandos on board.

In order to evade Turkish forces, the Greek planes flew in low when reaching Cyprus, with no communications and the lights switched off as they headed for Nicosia airport.

The Noratlas came under a barrage of anti-aircraft fire as the Greek Cypriots mistook the aircraft as hostile. It crashed close to the runway at around 3:00 am.

All but one of the 28 commandos and four crew on board were killed. One soldier miraculously survived after jumping out of the burning aircraft before it smashed into the ground.

The remains of those onboard were thought to be buried at a nearby military cemetery in Lakatamia.

In 1979, some remains were sent back to their families in Greece, but only those of 12 commandos have been properly identified through DNA sampling.

A search for the others at Lakatamia in May failed to locate any remains -- so the hunt has switched to the Makedonitissa cemetery and war memorial, adjacent to the now defunct airport which serves as a United Nations compound.

The memorial was built over the site where the plane went down and was buried.

- 'Send them home with honour' -

Cypriot humanitarian affairs commissioner Fotis Fotiou said an initial search yielded positive results -- a 50-centimetre (20-inch) piece of the Noratlas was found using a metal detector.

"The findings are positive in that the first indications show that the doomed aircraft is here," Fotiou told reporters on Thursday during a visit to the excavation site.

He said there was danger involved in the project as there were explosives and ammunition on the buried aircraft. There is no timeframe for when the excavation might be complete but authorities believe it should be finished by November.

"Certainly our aim is to find the fuselage and locate the remains of the fallen... we will do everything possible to find them and send them home with honour," Fotiou said.

A geophysical study will probe at a depth of 10-15 metres (30-50 feet) "to see if there is anything that will help scientists when advancing to the second phase," he said.

The second phase will begin next week, after foreign experts make the necessary calculations for trying to locate the plane, digging it up and hopefully recovering the remains.

The effort to recover the plane wreckage and identify the bodies has been welcomed by Greece and the soldiers' relatives.

During a ceremony at the site last month to launch the recovery drive, Greek ambassador Elias Fotopoulos said: "These brave men came to fight for Cyprus and were unjustly lost like so many others in 1974."