Russia on Friday condemned the latest reported massacre in Syria as a "bloody atrocity" which it blamed on forces that want to foment inter-ethnic conflict and civil war.

The Russian foreign ministry said it believed between 50 and 100 people were killed Thursday in the central village of Treimsa in an attack the rebels and the government of President Bashar Assad have both blamed on each other.

A Russian ship that tried to deliver attack helicopters to Syria last month has again left its Arctic port carrying the same military cargo, the state's military export agency said on Friday.

"The Mi-25 helicopters subject for return to Syria after their repair are currently aboard the Alaed, which is sailing from the port in Murmansk to another port in Russia," Interfax quoted a Rosoboronexport statement as saying.

U.N.-Arab League special envoy Kofi Annan is set to hold talks on Monday with Russian Foreign Minister Sergei Lavrov, Annan’s spokesman confirmed.

Ahmed Fawzi told Agence France Presse that the two will meet on Monday in Moscow.

Russia rejects as unacceptable the text of a Western-backed U.N. Security Council resolution on Syria and will use its veto if the draft is brought to a vote later Thursday, a deputy foreign minister said.

"If they decide this (a vote on Thursday) -- knowing that for us the text is unacceptable -- then we will not allow it to pass," Deputy Foreign Minister Gennady Gatilov told the Interfax news agency.

Turkish Prime Minister Recep Tayyip Erdogan leaves for Russia next Wednesday to discuss the developments in Syria with Russian President Vladimir Putin, his office announced Thursday.

"Significant regional and international developments led by Syria are on the table to be discussed thoroughly," during Erdogan's visit, the written statement said.

Cuban leader Raul Castro sought on Wednesday to revive a historic but flagging friendship with Russia as he met Vladimir Putin for talks on economic relief for his sanctions-plagued communist state.

The Cuban leader's second visit to Russia since his 2006 assumption of power from older brother Fidel extends a recent revival of contacts that had ground to a halt when the Soviet Union fell apart two decades ago.

Syria's main exiled opposition group on Wednesday slammed Russia for giving a green light to violence after failing to convince Moscow to drop its support for President Bashar Assad.

Syrian National Council (SNC) chief Abdel Basset Sayda met Foreign Minister Sergei Lavrov in rare talks at the Russian foreign ministry but could not detect any shift in the Russian policy that has angered opponents of Assad.

The United States is aware of a Russian naval flotilla headed for a Syrian port but does not yet see cause for concern, the White House said Tuesday.

"We currently have no reason to believe this move is anything out of the ordinary but we refer you to the Russian government for more details," Erin Pelton, a spokeswoman for the National Security Council, told Agence France Presse.

Residents of a flood-devastated Russian region on Tuesday picked through damaged homes and collected donated clothing amid ongoing criticism of the way officials handled the disaster.

In the worst affected town of Krymsk, the lack of sanitation and high temperatures provoked fears of a disease epidemic, and officials sought to allay the concerns.

Russia has sent a naval flotilla of six warships led by an anti-submarine destroyer to its naval base at the Syrian port of Tartus, the Interfax news agency reported Tuesday.

The Admiral Chabanenko and three landing craft have left their home port of Severomorsk in the Arctic Circle on their way to the Mediterranean where they will be joined by the Russian patrol ship Yaroslav Mudry as well as an assistance vessel, a military source told the agency.