The United States called on Cuba on Wednesday to allow imprisoned contractor Alan Gross to travel home to attend his mother’s funeral as a humanitarian gesture, AFP reports.

Gross, 65, was sentenced to 15 years in prison in Cuba in 2011 after being convicted of “acts against the independence or territorial integrity of the state” for allegedly distributing communications equipment as a contractor for USAID.

Washington has repeatedly called for his release, and on Wednesday State Department spokeswoman Jen Psaki offered “our deepest and sincerest condolences” following the news that his 92-year-old mother, Evelyn, had died after a long battle with lung cancer.

“We obviously feel it is a tragedy that he was unable to be home in the United States at his mother’s bedside for her passing,” Psaki was quoted by AFP as having told reporters.

“We’ve urged the Cuban government to grant Mr. Gross a humanitarian furlough so that he can travel to the United States and be with his family during this time of mourning.”

Psaki would not say whether Washington would provide guarantees that Gross would return to Havana to serve the rest of his sentence.

Gross’s family said the news of his mother’s death “is a devastating blow for Alan and our family.”

“I am extremely worried that now Alan will give up all hope of ever coming home and do something drastic,” his wife Judy said in a statement.

“Surely, there must be something President (Barack) Obama can do to secure Alan’s immediate release,” she added.

The family said Cuban officials had refused to give Gross a chance to visit his mother while she was still alive, despite repeated pleas after she was diagnosed with cancer.

Gross ended an eight-day hunger strike on April 11 to press for his release from prison. That hunger strike ended after a telephone conversation with his mother.

Gross’s family and US officials have also raised concerns about his own health. He was arrested in 2009 and is said to have lost more than 100 pounds (45 kilos) in weight. He suffers from chronic pain and the family are concerned that he is losing his will to live.

The Cuban government has expressed its willingness to free Gross in exchange for the United States free the so-called “Cuban Five”, intelligence agents convicted in a 1998 U.S. spy case.   

Havana acknowledges the five men – two of whom have been released after serving their sentences – were agents but says they were spying on “terrorist” exiles and hails them as national heroes. 

Secretary of State John Kerry has said in the past that Washington would work to free Gross but outright rejected a deal with Havana to swap him for the five Cuban spies.