Palestinians say Israel has severely curtailed gas supplies to the occupied Gaza Strip this winter, fueling a major disruption to ordinary life for most families and exacerbating the harsh impact of the cold weather.

Tholfikar Sweirjo, a member of the leftist Popular Front for the Liberation of Palestine's committee in Gaza, told Al Jazeera the amount of gas entering Gaza has been decreased by at least 50 percent since early December.

"People are suffering from the shortage ... especially because a lot of cars had been converted to use gas instead of petrol due to the high prices of petrol," he said.

Sweirjo accused Israeli authorities of causing this gas shortage to intensify pressure on Gaza in a bid to push people against Hamas, the group that governs the strip.

His statement came a week after the International Middle East Media Center quoted Mohamed al-Abadaleh, a spokesman of an association of fuel and gas station owners in Gaza, as saying: "It is week four since the Israeli authorities severely decreased cooking gas supplies for the Gaza Strip."

He also said the amount of gas allowed into the Palestinian territory is only 15 percent of what is needed normally.

The Israeli Ministry of Energy has not responded to Al Jazeera's requests for comment.

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Ramy Abdu, director of the Euro-Mediterranean Human Rights Monitor who is based in Gaza, told Al Jazeera more than 20 percent of households in the strip do not have any gas, as well as hospitals and schools.

"Normally we wait a couple of days to obtain our gas ration, but for many it is now taking weeks... We are talking about a permanent shortage during winter," he said, adding some restaurants have been forced to close.

Abdu said a shortage of electricity has worsened the crisis, since people have to rely more on gas.

"There has been a deteriotation in electricity supply... Normally we have eight to 10 hours of electricity in a day, and now it's four to eight hours."

He also said Gaza's agricultural sector - which depends heavily on gas to run greenhouses, especially since Israel sprayed herbicides to destroy vast swathes of crops near the border as part of a "no-grow zone" - has been further hurt by the gas crisis.

"Over the last 10 years, Israel has imposed a blockade that has made life in Gaza miserable to humiliate and subjugate the people," Abdu said.