By Phil Stewart and Gleb Bryanski
MOSCOW (Reuters) - The United States and Russia clashed over Libya Tuesday, with Moscow advocating a ceasefire and U.S. defense chief Robert Gates saying some Russians had swallowed Muammar Gaddafi's "lies" about civilian deaths.
Russian President Dmitry Medvedev, after talks with Gates at his residence outside Moscow, accused coalition forces of carrying out "indiscriminate" air strikes.
Prime Minister Vladimir Putin unleashed new criticism of the biggest armed intervention in the Arab world since the U.S.-led invasion of Iraq in 2003, saying those responsible for civilian deaths should "pray for the salvation of their souls."
The tough talk added to criticism from other emerging powers such as China, India and Brazil of coalition bombings meant to destroy Gaddafi's air defenses and create a no-fly zone.
Russia abstained in the U.N. Security Council vote last week allowing military action, but Putin lambasted the resolution on Monday and compared it to "medieval calls for crusades."
Those remarks triggered a rare rebuke from Medvedev, revealing a rift in Russia's ruling tandem ahead of a 2012 election, but the two closed ranks on the issue Tuesday.
"The President of the Russian Federation is in charge of foreign policy, and there can be no division there," Putin, visiting Slovenia, said in remarks televised live in Russia.
President from 2000-2008, Putin is widely seen as Russia's paramount leader and has hinted he will return to the Kremlin in the 2012 vote or endorse Medvedev for a second term.
He ramped up his rhetoric over Libya, suggesting both Gaddafi's government and the West would face judgment.
"I think we all should be thinking about the casualties, whose quantities are being multiplied both as a result of a civil war ... and as a result of rocket and bomb attacks on the country's territory," Putin said.
"Those who are involved in this tragedy should be thinking about that first of all -- they should think about it and pray for the salvation of their souls."
Medvedev, more quietly, also criticized the operation.
"Medvedev voiced his concern over how the U.N. Security Council resolution on imposing a no-fly zone is being implemented, (and) possible deaths among the civilian population in connection with the indiscriminate use of force by aviation," the Kremlin said after his meeting with Gates.
Defense Minister Anatoly Serdyukov drove home the issue in talks with the U.S. defense secretary earlier in the day, saying civilian deaths "should not have been allowed to happen."
Russia believes "that an immediate ceasefire and a dialogue between the belligerent parties is the surest path to the reliable security of civilians," he said.
Gates told Serdyukov the intensity of the fighting should decrease in the coming days and assured Moscow coalition forces were doing their best to avoid civilian casualties.
In blunter remarks later, he said Gaddafi was lying.
"We've been very careful about this and it's almost as though some people here are taking at face value Gaddafi's claims about the number of civilian casualties, which as far as I am concerned are just outright lies," Gates told reporters.
"It's perfectly evident that the vast majority, if not nearly all, civilian casualties have been inflicted by Gaddafi."
U.S.-Russia ties hit a low with Russia's 2008 war against pro-western Georgia but have improved under presidents Medvedev and Barack Obama, whose 'reset' of relations was crowned with a treaty cutting nuclear arms that came into force last month.
(Additional reporting by Gleb Bryanski in Brdo Pri Kranju and by Alexei Anishchuk, Guy Faulconbridge and Steve Gutterman in Moscow; Editing by Mark Trevelyan)