An unmanned supply ship has burned up on re-entry over the Pacific Ocean, a week after the spacecraft suffered a communications failure, the Russian space agency has said.

"The Progress M-27M spacecraft ceased to exist at 05:04 Moscow time on 8 May 2015. It entered the atmosphere... over the central part of the Pacific Ocean," Roscosmos said in a statement.

Almost all similarly-sized spacecraft disintegrate in the atmosphere or land in the oceans, which cover most of the Earth's surface.

Russia sends three or four such spacecraft per year to supply the International Space Station.

After making the delivery they plummet back to Earth, burning up in the atmosphere above the Pacific Ocean.

The spacecraft, a Soviet design generally known for its reliability, blasted off for the ISS on  April carrying oxygen, water, spare parts and other supplies for the orbiting space laboratory, which has a crew of six international astronauts.

A few hours after the launch, mission control lost contact with it.

A special commission is looking into the incident, the deputy head of Roscosmos has said.

Sources in the space industry told Russian news agencies that the accident was caused by a problem with the Soyuz rocket carrying the cargo ship into orbit, rather than the supply vessel itself.

A source close to the commission told Interfax news agency on Thursday that the rocket exploded seconds before it and the Progress vessel were due to separate.

The same type of rocket is used for manned ships, meaning any problem with it has to be investigated before further manned launches.

The ISS crew is not in immediate danger of running out of supplies as a US supply ship could bring replenishments by June 19.

But a source in the space industry told Interfax news agency on Tuesday that mission control had nonetheless told the crew to conserve resources.

TASS and Interfax news agencies cited sources as saying the next launch of astronauts to the station could be delayed over the glitches.

Russia has recently suffered a series of problems exposing shortcomings in its space programme.

A Progress supply ship crashed in Siberia shortly after launch in 2011. Moscow has also lost several lucrative commercial satellites.

Since the mothballing of the US Space Shuttle programme, Moscow has had a monopoly on sending astronauts to the ISS from its Baikonur cosmodrome in Kazakhstan.