(L to R) Yaniska Lugo, of the Martin Luther King Center, Manolo de los Santos, board member of the Pastors for peace and Nacyra Gomez, of the Presbyterian Cuban Church attend a news conference in Havana, Cuba, September 7, 2016. REUTERS/Enrique de la Osa

HAVANA (Reuters) - The Cuban Council of Churches denounced the U.S. government on Wednesday for threatening to strip tax exempt status from Pastors for Peace, a group that has delivered humanitarian aid to Cuba for decades in defiance of Washington’s sanctions.

Last month, the Internal Revenue Service (IRS) notified the group’s parent organization, the Inter-religious Foundation for Community Organization, that its status was in jeopardy because it had never requested permission from the U.S. Treasury Department to send aid. The IRS said it had been investigating the group since 2009.

Since 1992, well before the thaw in relations with Cuba under President Barack Obama, Pastors for Peace has run caravans through U.S. cities to collect donations, then crossed the border with Canada or Mexico and sent school buses, computers, medicines, and other goods on to the Communist Party-ruled Caribbean island.

The organization has refused to ask permission from the U.S. government to deliver the aid or travel to Cuba in protest of the U.S. trade embargo.

“I do not understand how at this moment, when the Obama Administration’s policy is to seek understanding, that on the other hand they are taking these types of measures against institutions that have created an understanding between our peoples,” Joel Ortega Dopico, President of the Cuban Council of Churches, said at a press conference in Havana.

Cuba and the United States began normalizing relations in December 2014 after 18 months of secret talks and have since restored full diplomatic ties. The countries had been hostile for more than five decades, since Fidel Castro ousted U.S.-backed dictator Fulgencio Batista in a 1959 revolution that steered the island on a communist course and made it a close ally of the Soviet Union during the Cold War.

There have been numerous skirmishes between Pastors for Peace and U.S. authorities at the border, temporary detentions and confiscations of aid over the years, but never prosecutions or other legal actions taken against the group or its members.

“It is not up to the IRS to decide what we can bring to Cuba and in what way,” Manolo de los Santos, in charge of Cuba for Pastors for Peace, said in Havana.