Poland's gas monopoly says that Russian natural gas deliveries dropped by 45 percent on Wednesday, the third day of decreases amid concern Moscow is piling on political pressure over the crisis in Ukraine.

The company, PGNiG, said Thursday it has received no notification of reductions from Russian supplier Gazprom. On Wednesday, PGNiG said it was seeking an explanation but Gazprom denied any fall in exports. Some commentators say Russia is trying to punish Poland for selling gas on to Ukraine.

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

Poland is compensating the shortfall by importing more gas from Germany and the Czech Republic.

Domestically, experts say there is no need for immediate concern because the weather is warm and gas storage tanks are full.