A military aircraft carrying 27 people including top members of the Kazakhstan border guard crashed Tuesday in the south of the country with all those on board believed dead, officials said.

The KNB security service said the An-72 military transport was carrying seven crew and 20 servicemen, including the acting head of the Kazakh federal border service Turganbek Stambekov.

The Interfax-Kazakhstan news agency said those on board also included one of Stambekov's deputies, as well as top regional guards commanders.

The plane crashed 20 kilometres (12 miles) from Shymkent airport in the south of Kazakhstan where it had been due to land after a flight from the capital Astana.

Kazakhstan's KTK television said the plane fell from a height of 800 metres (2,600 feet) and that weather around the airport at the time was very poor.

There was no immediate explanation for the crash but Kazakh military prosecutors said they had opened a criminal case into a possible violation of aviation rules or flight preparation.

Prosecutors confirmed the plane belonged to the KNB (Committee of National Security) which is the Kazakh successor to the Soviet-era KGB and is responsible for border security.

Eyewitness Baurzhan Dosov, whose home is near the crash area, told state television that he heard a noise like an explosion and then witnessed a scene of carnage.

"I was there 15 minutes ago. There are military hats everywhere and pieces of human flesh. Just like meat. The fire is still blazing," he told KTK television.

He described how he heard the plane "flying above me and then four seconds later there was a kind of explosion."

A security source told the Interfax news agency that all those on board were killed. KTK also reported there were no survivors.

"According to the latest information none of those on board survived," KTK said.

This was not confirmed explicitly in the KNB statement, though it made no reference to any chance of survivors.

"The emergency services are working at the scene of the incident. An investigation is in progress," the KNB said, without giving more details.

It said that the crash took place at 6:55 pm local time (1255 GMT).

KTK said the plane was already on a fourth loop of the landing strip, possibly implying the pilot had been doing circles, waiting for a chance to land in bad weather.

The Kazakh border guard service was already hit this year by tragedy with the mysterious killing of 14 of its servicemen in May at a border post in the remote Tian Shan mountains.

A border guard, Vladislav Chelakh, 20, was this month sentenced to life in prison for the killings but the defence argued he was being made a scapegoat for security failings higher up.

He denied involvement in the murders and said that the post was shot at by hostile unidentified people in civilian clothes, while he was the only one who could escape.

In an often macabre trial, the defendant at one point tried to cut his wrists open in court and attempted to hang himself in the detention centre.

Stambekov was only appointed to his post by presidential decree in June on an acting basis after the border post massacre.

Aviation disasters remain a scourge across the former Soviet Union due to ageing hardware that often has not been replaced since the fall of the Soviet regime, as well as human error.

In November, eight people were killed in Kazakhstan when a Russian-made Mi-8 helicopter crashed while carrying out a pipeline surveillance mission.