Ukraine says fighter jet shot down by missile from Russian plane

Also, Ukrainian forces took missile fire from inside Russia on Thursday, according to the Ukraine Security Council.

A Ukrainian fighter jet was shot down by an air-to-air missile from a Russian plane and Ukrainian troops were fired upon by missiles from a village inside Russia, a spokesman for Ukraine's Security Council said Thursday.

The alleged episodes mark what Ukraine says is mounting evidence that Moscow is directly supporting the separatist insurgents in eastern Ukraine who have been seen to have substantial quantities of powerful weapons in recent weeks.

Security Council spokesman Andrei Lysenko said the pilot of the Sukhoi-25 jet hit by the air-to-air missile Wednesday evening was forced to bail after his jet was shot down. He said the rockets launched at Ukrainian troops were fired from the Russian village of Kuibyshevo.

Pro-Russia rebels, meanwhile, claimed responsibility for strikes Wednesday on two Ukrainian Sukhoi-25 jets.

The Defense Ministry said the second jet was hit by a portable surface-to-air missile, but added the pilot was unscathed and managed to land his plane safely

Moscow denies Western charges that is supporting the separatists or sowing unrest in its neighbor. The Russian Ministry of Defense could not be reached for comment Thursday about the latest accusations and Russia's foreign ministry did not respond to multiple requests for comment.

Earlier this week, Ukraine said a military transport plane was shot down Monday by a missile fired from Russian territory. Security Service chief Valentyn Nalyvaichenko said he had "unconditional evidence" that Russia was involved in downing that craft.

The rebels are known to possess portable anti-aircraft rocket launchers, but Ukrainian officials say that kind of weapon would have been unable to reach the plane at the altitude at which it was flying Monday. Aviation experts, however, have questioned whether the stricken transport plane was flying at the altitude Ukrainian officials had claimed.

Although the pro-Russia insurgents fighting the government in Kiev suffered a major setback earlier this month when they abandoned their stronghold in the city of Slovyansk, they still appear well-supplied militarily and have incurred heavy losses among government troops.

An Associated Press reporter on Thursday saw seven rebel-owned tanks parked at a gas station outside the eastern Ukrainian town of Snizhne. In the town, he also observed a Buk missile system, which can fire missiles up to an altitude of 22,000 meters (72,000 feet).

Ukraine's border service said Thursday it has evidence that five Grad multiple-rocket launchers and two armored personnel carriers were brought across the border Wednesday from Russia.

"Having crossed 60 meters (yards) over the border, they fired in the direction of Ukrainian army positions," the border service said in a statement. "In the location from which they fired, we found fragments of missiles and the traces of burned ground."

The US slapped tougher sanctions against Russia on Wednesday for its actions in Ukraine. That prompted a strong reaction Thursday from Russian President Vladimir Putin, who said the sanctions will hamper bilateral relations and hurt not only Russian but also American businesses.

Russia's benchmark MICEX was down 2.4 percent in trading late Thursday after news of the sanctions while Russia's biggest oil company, Rosneft, was 4.4 percent down.

The US sanctions target Rosneft and another major Russian energy firms, a pair of powerful financial institutions, eight weapons firms and four individuals.

The US penalties, however, stopped short of the most stringent actions the West has threatened, which would fully cut off key sectors of Russia's oil-dependent economy. But officials said those steps were still on the table if Russia fails to abide by the West's demands to stop its support for the pro-Russia insurgents.