Pussy riot member Nadezhda Tolokonnikova now missing for more than three weeks – with her disappearance sparking fears some of the Greenpeace 30 could also be 'lost'

The jailed Pussy Riot musician Nadezhda Tolokonnikova has now been “lost” in the Russian penal system for more than three weeks, and her disappearance has led to fears for the safety of other high-profile prisoners.

Last week, reports emerged from Ms Tolokonnikova’s husband, Peter Verzilov, that his wife could have been transferred to a remote detention facility in the heart of Siberia, where authorities could “cut her off from the outside world”.

It has been 23 days since Mr Verzilov said he last heard from or saw the band member. She is serving a two year sentence for “hooliganism motivated by religious hatred”, after Pussy Riot performed songs in Moscow’s largest cathedral which called for the Virgin Mary to remove President Vladimir Putin from office.

Now the mother of one of the British men detained following a Greenpeace protest on a Gazprom arctic oil rig has expressed her concern some of those prisoners will also be “lost” in transportation.

Sue Turner, the mother of second engineer Iain Rogers, added that the consular support she had received from the British authorities had been “patchy”.

A total of 30 people on board the Greenpeace ship Arctic Sunrise were taken into custody in September.

The group of 28 activists and two journalists were being held in Murmansk but have now embarked on a 27-hour train journey to St Petersburg around 800 miles away.

While they are due to arrive at noon local time tomorrow (8am GMT), Ms Turner feared that some of the group might similarly be made to disappear during the journey.

She said: “I'm just worried that they are going to lose some of them on the way to St Petersburg. I won't be really happy until they all arrive there and we know where all 30 are.

“They have lost a Pussy Riot member, she's disappeared. What's to say that they cannot lose some of our Arctic 30 while they are transporting them from Murmansk to St Petersburg and then onto maybe different prisons in St Petersburg?

“They are not necessarily going to be sent to the same place. We were told that they were hoping they would be sent to the same place but we have got no guarantee of that at all and no guarantee that their conditions are going to be any better.”

When asked what motive the Russian authorities could have for losing some of the activists, she replied: “It would make life easier for them. They would have less people to worry about, less people to prosecute.”

The families of all six UK nationals being held by the Russian authorities met with Europe minister David Lidington yesterday.

Ms Turner said: “The consular support initially was very patchy. I don't think it was good enough.

“It has improved since our last meeting in London and probably it will improve now the minister knows our feelings about the lack of communication, lack of honesty with the consular staff.”

The relatives of father-of-three activist Phil Ball also met with David Cameron as they are from his constituency of Witney in Oxfordshire. But they admitted that they knew how little influence the Prime Minister – and indeed the Foreign Office – can have on matters in the Russian case.

Mr Ball’s brother Steve said: “He can have no grounds for optimism. The gentle influence that the British Foreign Office can have is being placed at the moment. Until we get a sentence there is nothing for us to react to.”

The Britons being held are Mr Ball, 42, Mr Rogers, 37, from Exeter, video journalist Kieron Bryan, 29, from Devon, and activists Alexandra Harris, 27, originally also from Devon, Frank Hewetson, 48, from London, and Anthony Perrett, 32, from Newport.

Additional reporting by the Press Association