TEHRAN, Iran (AP) — Iran on Saturday denounced recent U.S. allegations that it was providing covert aid to help Venezuela overcome gas shortages as “baseless" without directly addressing them.

Secretary of State Mike Pompeo last week said “multiple aircraft" belonging to Iran's Mahan Air had transferred ”unknown support" to Venezuela's government. He called for a halt to the flights and for other countries to bar overflights by Mahan Air.

The Associated Press reported last month that Mahan Air was delivering key chemical components used for producing gasoline to help revive an aging refinery in the South American country, which is in the grip of a severe economic crisis.

Venezuela has been suffering from widespread gasoline shortages despite having the world's largest oil reserves.

Both Iran and Venezuela are under heavy U.S. sanctions, and have had close relations for the last two decades.

Iran's Foreign Ministry tweeted that the “baseless comments were made in order to prepare the ground for mounting U.S. pressure on the Venezuelan government.”

Another statement said the U.S. intended to “obstruct the Venezuelan government's plan for reviving the country's refineries." The statements did not directly address the allegations or elaborate on the nature of the cooperation between the two countries.

The Trump administration is pursuing a “maximum pressure” campaign aimed at ousting Venezuela's socialist president, Nicolás Maduro, and considers opposition leader Juan Guaidó as the nation’s legitimate leader. The U.S. and a coalition of nearly 60 nations say Maduro clings to power following a 2018 election that critics consider a sham because the most popular opposition politicians were banned from running.

The Trump administration imposed heavy sanctions on Iran after withdrawing from Tehran's 2015 nuclear deal with world powers.