Russian Foreign Minister Sergei Lavrov accused the United States on Monday of plunging the Middle East into chaos and fueling the rise of extremists because of its drive to dominate the world.

Lavrov leveled the fierce criticism of Washington's policies at a special U.N. Security Council debate on maintaining international peace and security.

The United States and Iran said Monday they had made some progress in the latest round of talks on Tehran's nuclear program, but warned there was still a long way to go to reach a final deal.

Negotiators for Iran and six world powers have held a range of meetings in Geneva since Friday, and plan further talks in the city next week, a senior U.S. administration official said.

Russia has offered Iran advanced surface-to-air missiles after scrapping a similar deal in 2010 because of U.N. sanctions over Tehran's nuclear program, the state defense company said Monday.

Any such a deal is likely to go down badly in Washington as Western countries seek to keep up the pressure on Iran to agree a comprehensive deal on its nuclear activities.

Germany's foreign minister warned Sunday in comments to a newspaper that any attack on the eastern Ukrainian city of Mariupol would be a clear violation of a week-old ceasefire accord.

Asked by Germany's Bild newspaper where, for him, the red lines in the Ukraine conflict lay, Frank-Walter Steinmeier said they had been drawn in the Minsk ceasefire deal that Germany helped broker.

A senior British minister ruled out sending arms to Ukraine Sunday as the United States and European nations sought ways to pressure Russia over the conflict in the ex-Soviet republic's east.

William Hague, who was foreign secretary until last year and is still a minister seen as close to Prime Minister David Cameron, said governments should think "very, very carefully" about such a move.

Thousands of pro-Kremlin activists took to the streets of central Moscow on Saturday vowing to prevent a Ukraine-style uprising in Russia.

The rally by the Anti-Maidan movement marked one year since scores of demonstrators were gunned down in Ukraine's pro-Western uprising that came to be known as the Maidan protests.

Ukraine lost 179 troops in a month-long battle with pro-Russian rebels that ended in defeat over the key eastern town of Debaltseve, an advisor to the country's president said.

If the figure is confirmed, it would represent one of the bloodiest losses suffered by the Ukrainian side in the 10-month conflict. 

Pro-Russian rebels said they will swap prisoners with the Ukrainian side Saturday as part of a battered truce that the West hopes will cool a deadly conflict that has poisoned relations with Moscow.

"Today (Saturday) there will be an exchange between us and the Ukrainian side," said the rebels' official for human rights, Daria Morozova.

Germany and France demanded Friday that a crumbling Ukraine truce be "fully respected" even as pro-Russian rebels celebrated a battlefield victory in a strategic town and exchanged artillery fire elsewhere with government troops.

"The ceasefire has been violated several times," French President Francois Hollande said in a joint Paris media conference with German Chancellor Angela Merkel.

EU head Donald Tusk said Friday he was consulting EU leaders on the next steps to take to increase "the costs of aggression" in eastern Ukraine where a ceasefire has failed to stop the fighting.

With the latest peace accord breached more than 300 times, "we are clearly reaching a point when further diplomatic efforts will be fruitless unless credibly backed up by further action," Tusk said in a statement.