A passenger train on its way to Moldova has collided with a freight train near Moscow, killing at least six people and injuring many others, a spokeswoman for Russia's Emergencies Ministry said.

The collision occurred after 15 freight-train carriages derailed on Tuesday near the town of Naro-Fominsk, 55km southwest of Moscow, according to Russian Railways.

An official from the state-owned railway told reporters at the scene that five people were killed immediately and a sixth died later in hospital.

Russian Health Minister Veronika Skvortsova said it appeared that all six people who were killed were Moldovans.

"We tried to use an emergency brake. We couldn't see anything ahead, there was lots of dust. Visibility was zero," state-run RIA news agency quoted one of the drivers of the passenger train as saying.

Viktor Yatsenko, an official with Russia's Emergencies Ministry, had earlier told a televised conference with other officials that 45 people had been hurt in addition to the dead.

He said 15 of the injured were seriously hurt.

Rescue coordinator Vadim Andronov said the death toll was likely to rise.

"One of the carriages of the passenger train was crushed by the freight train wagons. Rescuers are working to pull out injured people being crushed by the wagon," he said.

A criminal investigation into the crash has been launched.

Source: Agencies