Russian Foreign Minister Sergei Lavrov on Wednesday criticized President Bashar Assad for the "big delay" in reform in Syria, saying Damascus was failing to swiftly follow Moscow's advice.

"Unfortunately, our advice is reflected practically in his actions far from all the time and far from in a timely manner," Lavrov told the lower house parliament in a rare show of public frustration with the Syrian leader.

The United States has asked Russia to warn Iran it has a last chance in negotiations expected in April to avoid military strikes against its nuclear program, a report said on Wednesday.

Russia's Kommersant daily said U.S. Secretary of State Hillary Clinton had told Russian Foreign Minister Sergei Lavrov that the talks between Iran and world powers were a "last chance" to resolve the crisis.

U.S. senators are urging the Pentagon to cancel a contract with a Russian company approaching $1 billion to buy helicopters for Afghanistan, voicing outrage over Moscow's arming of Syria.

"U.S. taxpayers should not be put in a position where they are indirectly subsidizing the mass murder of Syrian civilians," 17 senators across party lines wrote Monday in a letter to Secretary of Defense Leon Panetta.

Russia said Tuesday it will press Syria to accept international monitors who could observe the implementation of a "simultaneous" ceasefire between government troops and rebels.

Foreign Minister Sergei Lavrov said Russia was discussing the proposal with both the Arab League countries and at the United Nations, where the Security Council debated the crisis on Monday.

Russia's crisis-hit space agency intends to send its first manned mission to the Moon and deploy research stations on Mars under an ambitious plan presented to the government this month.

The Kommersant daily said the mission statement from the Roscosmos space agency through 2030 reveals no financial details but includes plans to find outside sources of funding that do not put additional pressures on the budget.

One of Russia's most modern military helicopters has crashed during a training exercise, killing its two-man crew, official said Tuesday.

The Ka-52 Alligator two-seater, which entered serial production in 2008, went down in the central Tver region on Monday evening, the local investigative committee said in a statement.

Progressive Socialist Party leader MP Walid Jumblat urged on Monday Syria’s Druze population to abandon the ruling regime, warning them against “getting their hands covered with the blood of the Syrian people.”

He told France 24 television: “I caution the Druze against getting embroiled in any sectarian strife with the Sunnis because that will spell their end.”

Lebanon welcomes the Russian initiative on Syria that was adopted by Arab states during Saturday’s meeting in Cairo, Foreign Minister Adnan Mansour said on Sunday, while reiterating insistence on “Lebanon’s stances concerning the previous resolutions” passed by the Arab League.

“Lebanon welcomed the Russian initiative and the points agreed on with the Russian side, reiterating its stances on the previous resolutions,” Mansour said in Beirut, after taking part in the Cairo talks between Russian Foreign Minister Sergei Lavrov and his Arab counterparts.

The Obama administration and its allies are engaged in serious discussions about potential military involvement in Syria, The Washington Post quoted officials as saying.

“Possibilities include directly arming opposition forces, sending troops to guard a humanitarian corridor or “safe zone” for the rebels, or an air assault on Syrian air defenses,” according to the officials from the U.S. and other nations opposed to Syrian President Bashar Assad.

French Foreign Minister Alain Juppe implicitly slammed Russia's stance on a draft U.N. resolution on Syria on Saturday, saying there were no grounds to demand a simultaneous halt to violence.

"Currently any possibility of reaching an agreement over a Security Council accord is blocked," Juppe, who will be in New York on Monday to discuss the draft, said at the close of EU foreign ministers' talks in the Danish capital.