* Hundreds of activists detained at rally Monday
* Kremlin worried over upheaval in Ukraine
MOSCOW, Feb 25 (Reuters) - Russian opposition leader Alexei Navalny was jailed for a week by a court on Tuesday for resisting arrest at a protest over the convictions of activists for attacking police at a 2012 rally against President Vladimir Putin.
Moving swiftly to curb the protest, Russian riot police on Monday detained hundreds of Kremlin opponents for demonstrating against what they called a "show trial" intended to discredit the opposition and quash dissent.
"7 days for Alexei @navalny," his spokeswoman, Anna Veduta, wrote on her Twitter feed.
The punishment handed to Navalny and others at the protest sends a signal that the Kremlin will not tolerate unsanctioned protests, with an eye on the upheaval in neighbouring Ukraine where demonstrations have unseated President Viktor Yanukovich.
Several other prominent opposition figures, including Boris Nemtsov, involved in the protest were ordered detained by between seven and 10 days.
The detentions have drawn criticism from Europe, adding to strains between Russia and the West at a time when they are deeply at odds over the future of Ukraine.
The Kremlin blames the bloodshed in Ukraine, where police were among at least 82 people killed in clashes in Kiev last week, on opposition leaders and the West.
Monday's ruling has been widely linked to the Kremlin's fear of seeing the turmoil in Ukraine repeated at home.
"Of course the punishment was influenced by events in Ukraine," said Mikhail Barshchevsky, a lawyer who is the government's representative to the higher courts.
He said the case was aimed at showing riot police that the authorities were on their side.
"Any regime must first and foremost take care that it is respected by the security forces, if it counts on their help in the event of mass rioting," told Ekho Moskvy radio. "That explains the sentences."
A judge had sentenced seven men on Monday to prison terms ranging from 2-1/2 to four years after finding them guilty of rioting and violence against police at a protest on May 6, 2012.
Kremlin critics say police started the violence at the rally on the eve of Putin's inauguration to a third Kremlin term.
Navalny, who led anti-Putin street protests in 2011-2012, has been restricted from leaving Moscow since his conviction in July for organising the theft of 16 million roubles from a timber firm in 2009, for which he received a suspended sentence.
If Navalny is found to be in violation of the terms of his suspended sentence, that may be commuted into real jail time. (Writing by Alissa de Carbonnel; Editing by Alistair Lyon)