By LAURA MILLS, Associated Press

MOSCOW (AP) — Russian officials struck a defiant note Monday after Western leaders threatened to further punish Moscow for escalated fighting in eastern Ukraine over the weekend.

In televised comments after a meeting with students in St. Petersburg, President Vladimir Putin said that Ukraine's army was at fault for the uptick in violence and accused it of using civilians as "cannon fodder" in the conflict.

"(Ukraine's army) is not even an army, it's a foreign legion, in this case a foreign NATO legion," Putin said. "They have totally different goals, connected to the geopolitical containment of Russia, which absolutely do not coincide with the national interests of the Ukrainian people."

That confrontational rhetoric came in the wake of Western threats that Russia would face further sanctions for its actions in east Ukraine, where 30 people were killed by rocket fire in the coastal city of Mariupol on Saturday. There was no fighting in Mariupol on Monday but Donetsk, the main rebel stronghold, was wracked by artillery explosions throughout the day.

Putin's stance was echoed by Foreign Minister Sergey Lavrov, who said during a press conference in Moscow that the tragedy in Mariupol was being manipulated to "whip up anti-Russian hysteria" in the West. Lavrov also blamed Kiev for the fighting, and said that the rebels were only responding to a government offensive.

"To expect that they (the rebels) would simply reconcile themselves to being bombed would be naive," he said. "They started to act... with the goal of destroying Ukrainian army positions being used to shell populated areas."

The Russian currency weakened on news of possible sanctions early Monday, tumbling by more than 3 percent to 65.7 to the dollar from 63.7. Russia's economy has been hit hard by existing Western sanctions and plummeting oil prices, and the ruble has already lost about half its value in the past year.

While sanctions are set to expire this summer, President Barack Obama said Sunday that Washington would work with its European partners to "ratchet up the pressure on Russia" in response to the latest violence. EU foreign ministers will hold an extraordinary session on Thursday to discuss the situation in Ukraine.

At least 5,100 people have been killed in eastern Ukraine since fighting began in April, but violence this week was the most intense since a cease-fire deal was signed in September.

Mariupol, a strategic port city on the Black Sea still controlled by Ukrainian forces, has been a symbolic bulwark against the separatist advance that if captured by the rebels would give them a land corridor to Russia-controlled Crimea. The city had been relatively quiet for months before Saturday's attack.

The Organization for Security and Cooperation in Europe's monitoring mission in east Ukraine has said the Grad and Uragan rockets that hit Mariupol were fired from areas under rebel control. Separatist leaders initially announced that they had begun an offensive on the city, but quickly backtracked and blamed Ukraine for the carnage after the extent of civilian casualties became known.

There was no fighting in Mariupol on Monday. A road leading out of the city into rebel territory was closed off by Ukrainian forces, making it unclear whether the rebels had advanced closer to the city outskirts. The city streets were quiet as the families of those killed Sunday gathered to bury their dead.

Ukrainian armed forces spokesman Vladislav Seleznyov said seven soldiers had been killed and 24 others wounded in the past day of fighting. He said 184 soldiers were in rebel captivity.

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Yuras Karmanau in Kiev, Ukraine and Evgeny Maloletka contributed reporting from Mariupol, Ukraine.