Alarming new traces of 'drilling' have been found on a Soyuz spacecraft docked with the International Space Station, Russian sources revealed today.

Moscow had already hinted at possible sabotage over damage found to the Soyuz MS-09 and a major whodunnit investigation is underway.

Officials have claimed the damage to the spacecraft appears to have been caused by a drill, and could have occurred on the ground pre-launch - or while in orbit.

Now a source close to the Russian space agency Roscosmos has admitted the damage was more extensive than previously thought.

'Traces of drilling have been found not only inside the spacecraft's living compartment,' said the source.

The damage was also 'on the screen of the anti-meteorite shield that covers the spacecraft from the outside and is installed 15 millimetres from the pressurised hull'.

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Russian astronaut Sergei Prokopyev showed the original 'drilled hole' during a video released by the space agency Roscosmos

A drop in pressure due to an air leak was first detected on the $150 billion (£115 billion) orbital station overnight on August 30.

The cause was later discovered to be a two-millimetre hole in the orbital compartment of the manned Soyuz MS-09 space vehicle, which has been docked to the space station for two months.

Russian cosmonauts quickly plugged the hole and restored pressure, patching it up with several layers of epoxy resin - a glue-like substance.

After the hole was sealed cosmonauts carried out photo- and video surveillance of the hole using an endoscope.

A Russian official said last week that the hole appeared to have been punctured using a drill, and could have been caused deliberately by someone on the ground.

Now a source says the extent of the damage was greater than experts first feared.

Sergei Prokopyev (pictured) explained on a video released Monday by the Russian space agency Roscosmos how the crew last week located and sealed the tiny hole that created a slight loss of pressure

'During the analysis of those images, traces of drilling were found on the anti-meteorite shield,' said the source, as cited by Russian TASS news agency.

'The top of the drill came through the pressure hull and hit the non-gas-tight outer shell.'

The latest disclosure comes as Russia was seeking to to calm speculation over the spacecraft damage.

Earlier this week space agency head Dmitry Rogozin held phone talks over the problem with NASA Administrator Jim Bridenstine.

Both side agreed to 'refrain from any premature conclusions and from presenting any explanations before the investigation is fully completed'.

Initially it was thought the damage could have been caused by a micrometeorite piercing the spacecraft.

This was ruled out and Rogozin - a close Vladimir Putin ally - raised the possibility of sabotage.

He asked: 'What was it: a defect or some intentional acts? Where were these acts carried out? On the Earth or already in orbit?

'Yet again, I am saying: we are not dismissing anything.'

The Soyuz MS-08 (pictured) left Earth on March 21 to transport three members of the Expedition 55 crew to the International Space Station

WHAT COULD HAVE CAUSED A HOLE IN THE ISS? Theory one - it was caused by a small meteorite A tiny hole appeared in a Russian space capsule locked to the ISS on 30th August. The 'micro fracture' believed to be around 2mm wide in the $150 billion (£115 billion) space station was discovered after astronauts noticed a drop in pressure. European Space Agency astronaut Alexander Gerst reportedly put his finger over the hole before crew patched it with tape. The hole was confirmed repaired by Friday (31 August) after cabin pressure returned to normal. It was initially believed to have been caused by a small meteorite and astronauts used tape to seal the leak after it caused a minor loss of pressure. Theory two - it was made deliberately while in orbit However, as the investigation went on it began to look like the hole was made from someone inside as opposed to outside, either back on Earth or in space, the Russian space agency claimed. Roscosmos chief Dmitry Rogozin said in September that the hole could have been drilled during manufacturing or while in orbit with a 'wavering hand'. He didn't say if he suspected any of the US crew, but the statement has caused some bewilderment. Sources suggest the question of how to fix the hole may have strained relations between Moscow and Houston. Rogozin has since reneged on his statement blaming the media for twisting his words and said that he 'never pointed the finger at U.S. astronauts'. Theory three - it was caused by a worker at Energia A leading theory from an unnamed source at Energia said the hole was made on the ground – potentially caused by 'deliberate interference' – with suggestions the person responsible may have already been identified. Another anonymous source said the hole was drilled by a worker who hid their mistake with a seal instead of reporting it. An unnamed source at Energia told the Russian news agency RIA Novosti that '[t]he hole was made on the ground'. According to the source, '[t]he person responsible for the act of negligence has been identified'. Another anonymous source said the hole was not made intentionally but by a worker who hid their mistake with a seal instead of reporting it. The patchwork repair lasted the trip up to the ISS but after three weeks in orbit gradually peeled away. Advertisement

Rogozin said it was 'a matter of honour...to find whoever was guilty' of causing the spacecraft damage - and 'whether it was deliberate'.

The Russian media even speculated that a US astronaut might have sabotaged the spacecraft to delay a possible early return to earth due to alleged sickness of one member of the ISS crew.

But Russia now appears to be focusing on possible damages during the last stage of works or during its 90-day stay in the checkout stand ahead of transportation to the Baikonur launch site in Kazakhstan.

Roscosmos director Dmitry Rogozin said that the hole could have been drilled during manufacturing or while in orbit. He did not say if he suspected any of the current crew of three Americans, two Russians and a German aboard the station (pictured)

An industry source denied damage was possible before this - and it is thought unlikely to have been tampered with at Baikonur.

'When Soyuz MS-09 just arrived to the final assembly workshop, it was photographed in detail,' said the source.

'No hole and no signs of drilling… were found.'