WARSAW, Poland (AP) — Russian natural gas deliveries to Poland dropped by 45 percent on Wednesday, the third day of decreases, heightening concerns that Moscow is piling on political pressure over the crisis in Ukraine.

Poland's state gas company, PGNiG, said Thursday it had received no notification from Russian supplier Gazprom. Gazprom has denied any fall in exports but has not provided further explanation.

Some commentators say Russia is trying to punish Poland for selling the gas on to Ukraine. Moscow is angry with the Ukrainian government for trying to quash a rebellion of pro-Russian separatists in the east, and with Poland and the EU for supporting Ukraine.

PGNiG spokeswoman Dorota Gajewska said it was the first time the company has seen such a drop in deliveries from Gazprom. She said lawyers were analyzing whether Poland should seek damages from Gazprom.

Deliveries dropped by 20 percent on Monday and 24 percent on Tuesday, PGNiG said.

Poland is making up for the shortfall by buying more gas from Germany and the Czech Republic, Gajewska said. She added that there is no need for immediate concern in Poland because the weather is warm and gas storage tanks are full.

Last year, Poland bought some 8.9 billion cubic meters of Russian gas, covering about 60 percent of its needs. Poland meets another 30 percent of its demand with gas it produces itself, and the remainder comes from other European countries, mainly Germany and the Czech Republic. Poland also has some 2.6 billion cubic meters of natural gas stored in gas tanks.