UK military sources and other NATO allies have expressed serious concerns over the security breach which German chancellor Olaf Scholz described as "very serious".

Berlin has launched an investigation after Russian media obtained a recording of the intercepted conversation between Lieutenant General Ingo Gerhartz, the head of the German air force, and three senior German air force officers.

Follow latest: Russia considering putting nuclear power station on moon

Miguel Berger, Germany's ambassador to the UK, told the BBC Radio 4's Today programme on Wednesday that the preliminary results of an investigation by military intelligence suggests one of the participants had likely dialled in using an insecure line.

He added that the German government had "no need to apologise" because the leak was down to "an individual mistake by one of the officers".

"I think that is a good lesson for everybody: never use hotel internet if you want to do a secure call," Mr Berger said.

The ambassador also said NATO allies need to be "careful not to fall into the Russian trap of creating division" after former UK defence secretary Ben Wallace said Germany was "pretty penetrated" by Moscow's intelligence services.

Mr Berger said: "It is extremely unhelpful what Ben Wallace has done.

"This is what Russia wants."

The ambassador added: "In the end, it was a very professional talk about the use of long-range missiles. But we have to be careful not to fall into the Russian trap of creating division, and regrettably, some people have fallen into this trap."

Mr Berger also said the publication of the call in Russian media was a "hybrid attack" by Moscow.

He added that German defence minister Boris Pistorius had called allies to explain Berlin's position over the leak.

Russia claimed the recording showed the direct involvement of the West in the Ukraine conflict.

A Russian foreign ministry spokesperson later said on social media: "We demand an explanation from Germany."

Read more from Sky News:
Into the grey zone - the murky evolution of warfare
Russian communists ask for probe into Stalin's death
Navalny's wife calls on Russians to protest

What was discussed in the call?

During the 38-minute recording, Lieutenant General Gerhartz reportedly says British troops have been "on the ground" in Ukraine.

He also talks about how the UK and France were delivering cruise missiles to the country.

The four senior German military officers are also reported to have discussed the prospect of Ukraine using German-made Taurus cruise missiles to hit the Kerch Bridge, which links Russia to the Crimean peninsula.

Mr Scholz has repeatedly ruled out sending Taurus missiles to Ukraine.