Two jailed Pussy Riot members could be freed early under a general amnesty backed by Russian President Vladimir Putin but anti-Kremlin ex-tycoon Mikhail Khodorkovsky is unlikely to benefit, according to a draft bill published Tuesday.

Far from being freed early under the amnesty, Khodorkovsky risks a third trial that could keep him in prison beyond his August 2014 release date after prosecutors revealed he was being investigated on new charges.

The Russian parliament on Tuesday published a draft proposal for a prison amnesty that would include Pussy Riot's Nadezhda Tolokonnikova and Maria Alyokhina, albeit just three months before their two-year sentences end.

The proposal does not list specific cases but says it applies to those convicted or charged with certain more minor offences such as hooliganism.

The Pussy Riot activists were convicted of hooliganism for a protest against Putin in a church. They could qualify for the amnesty on another count because both have young children. They are due to be freed in March after being refused parole several times.

They could still be excluded from the amnesty if courts rule that they committed serious breaches of rules in their penal camps, however.

The 30 Greenpeace crew members from 19 countries who have been bailed on hooliganism charges over a protest against Arctic energy drilling could be allowed to leave Russia after their case raised international concerns.

Greenpeace cautioned against being too optimistic, saying on Twitter: "Media reports on amnesty are all speculation until confirmed by Russian parliament."

Putin submitted the amnesty bill, which means its approval by parliament should be a formality.

The bill could also cover some of the activists detained in May 2012 at a Moscow protest against Putin ahead of his inauguration for a third term.

Russia will be keen to enjoy the blaze of publicity as it hosts the Sochi Winter Games next year -- without awkward questions about the jailings of Putin's foes.

The bill is timed to mark the 20th anniversary on Thursday of the adoption of Russia's post-Soviet constitution. Putin is due to give his annual state-of-the-nation address to coincide with the anniversary.

Russian human rights ombudsman Vladimir Lukin said that the amnesty could affect up to 22,000 people in Russian prison camps, pre-trial detention centres, or convicted without being jailed.

The amnesty will free around 1,300 convicted prisoners and a further 6,000 awaiting trial, the head of the ruling party faction in the Duma, Vladimir Vasilyev, was cited as saying by Interfax.

Khodorkovsky not eligible

But Khodorkovsky, who this year marked 10 years in prison and has been convicted twice of fraud and embezzlement, does not qualify because "his sentence was for more than five years," a lawmaker responsible for criminal legislation, Pavel Krasheninnikov, told the RIA Novosti news agency.

The Kremlin's human rights envoy Mikhail Fedotov also confirmed that Khodorkovsky would not be eligible for amnesty. His lawyers have already made clear they have no hope of the measure applying to their client.

But with less than a year left to serve, Khodorkovsky now risks a further trial.

Deputy Prosecutor General Alexander Zvyagintsev warned Friday that "there are several criminal cases under investigation involving him and several other people."

The Interfax news agency reported the new case involved charges of money laundering of $10 billion and Khodordovsky risked being given an additional sentence of up to seven years.

Khodorkovsky's supporters have long argued that he has been held in detention since 2003 and convicted in two fraud trials as punishment for daring to finance opposition to Putin's rule.

While his arrest did not cause much protest in Russia a decade ago, the country is currently in a completely different political climate after the mass demonstrations against Putin's rule from 2011-2012.