The Russian parliament on Tuesday gave preliminary approval to an amnesty that could pardon jailed members of the punk band Pussy Riot, but the move appears to be a largely symbolic effort to placate critics before the showcase Winter Games.

In the first of three votes, parliament voted unanimously in favour of the bill, a complicated piece of legislation that appears tailored to the band members and some other political prisoners — but that may pass only after the scheduled March release of the two band members still in jail.

In its current state, it would most likely not free the 30 crew members of a Greenpeace ship arrested after a protest in Arctic waters or most of the dozens of protesters arrested in the wake of massive protests last year against President Vladimir Putin.

Putin has been largely unyielding to Western criticism of his country's human rights records in the run-up to the games, defending an anti-gay law that has prompted calls for a boycott and overseeing a Kremlin crackdown on protesters and environmental activists. But the Kremlin is clearly sensitive about its international image ahead of the Sochi Olympics that start in February. It may see the limited amnesty as a way to soothe Western discontent without disappointing Putin's conservative support base.

The amnesty extends to mothers, pregnant women, older people and soldiers who are sentenced to less than five years for nonviolent crimes. Nadezhda Tolokonnikova and Maria Alekhina, the Pussy Riot members serving two years on charges of hooliganism for an irreverent 2012 anti-Putin protest at Moscow's main cathedral, both have children.

Exception to rule

But it could take up to six months to carry out the bill, while Tolokonnikova's and Alekhina's release was already slated for early March.

A separate article says that anyone charged with "hooliganism" or "participation in mass riots" can be freed. But the law would not guarantee freedom to people who are awaiting or facing trial. Such an exception would prevent others charged in what critics say are politically motivated trials from walking free any time soon.

That impacts the fate of the 30 members of the Greenpeace ship Arctic Sunrise, who face up to seven years in prison on hooliganism charges after a protest outside a Russian oil rig in Arctic waters. Greenpeace international lawyer Daniel Simons said in a statement last week that an amendment of the amnesty bill to include the Greenpeace detainees would be a "welcome development."

The bill would also not provide amnesty to most of the dozens of people who are on trial for participating in an opposition protest on Bolotnaya Square in May 2012. Seven of those involved in the so-called "Bolotnaya Trial" who face lighter charges — like participation in mass riots, which carries a sentence of up to eight years — could be released if the court hands down a sentence within six months. The case has already dragged on for more than a year.

Some lawmakers have already vowed to extend amnesty to those who are currently on trial, adding amendments to the bill ahead of a crucial second vote slated for Wednesday.

1st big amnesty in 1994

"There has to be a general principle: Amnesty must be extended to those who have been sentenced by the court as well as those who are on trial or under investigation," said Pavel Krasheninnikov, a lawmaker from the ruling United Russia party.

Russian parliament granted its first sweeping amnesty in 1994, when dozens of President Boris Yeltsin's opponents who had been jailed after the 1993 political standoff that ended in a military takeover of parliament were freed from prison.

Such legislation often acts as a political bellwether in a country where high-profile criminal cases can be politically charged. A bill passed in July granted amnesty to those accused of economic crimes, but noticeably passed over former oil tycoon Mikhail Khodorkovsy, who has spent over a decade in jail for what many see as punishment for his financial support of anti-Putin political groups in the early 2000s.

Legislators added a last-minute clause excluding amnesty for those who had been convicted twice, which would include the tycoon, who has been convicted in two separate fraud trials.