By Mariya Gordeyeva

KYZYL TU, Kazakhstan (Reuters) - A passenger plane crashed in thick fog near Kazakhstan's commercial capital Almaty on Tuesday and broke into pieces when it slammed into the ground, killing at least 20 people.

Private Kazakh airline SCAT said all 15 passengers and five crew were killed when the Canadian-built Bombardier Challenger CRJ-200 came down near the village of Kyzyl Tu about five km (three miles) from Almaty's airport.

"There was no fire, no explosion. The plane just plunged to the earth," Yuri Ilyin, deputy head of the city's emergencies department, told Reuters near the scene.

Parts of the plane could be seen in the thick snow. Tractors and other heavy vehicles were being used cut paths through the snow to the wreckage but journalists were prevented from going close.

It was the second fatal plane crash in the former Soviet republic in just a over a month.

Visibility at Kyzyl Tu was only about 20 to 30 meters (yards), and much of the area around Almaty was veiled in fog when the plane crashed at around 1 p.m. (2 a.m. ET)

"The preliminary cause of the accident is bad weather," Deputy Almaty Mayor Maulen Mukashev told reporters. "Not a single part of the plane was left intact after it came down."

The plane had been on its way from the city of Kokshetau in northern Kazakhstan to Almaty in the southeast, Mukashev said.

Ilyin put the death toll at 22 but SCAT and the office of the Central Asian country's prosecutor general said there had been only 20 crew and passengers on board.

SCAT, which has been operating since 1997, runs an extensive domestic service and has some international flights.

Alexander Gordeyev, deputy head of Almaty's airport, said the weather had been bad but planes were being allowed to land there.

A military transport airplane crashed in bad weather on December 25 near the southern Kazakh city of Shymkent, killing all 27 on board. Prosecutors have said a combination of technical problems, bad weather and human errors caused that accident.

(Reporting by Mariya Gordeyeva; Additional reporting and writing by Dmitry Solovyov; Editing by Timothy Heritage, John Stonestreet)