Associated Press

A lawyer for Alan Gross, who is serving 15 years for illegally bringing communications equipment to the island, said Richardson came Wednesday at Havana's invitation. The former governor would not confirm that in comments to The Associated Press, nor say what he hoped to accomplish on the trip.

Richardson, a former U.S. ambassador to the United Nations, has a long history winning the release of prisoners and a close working relationship with Cuba's leaders.

"I don't have any comment," a smiling Richardson said as he sipped a drink and smoked a Cuban cigar on the wide terrace of Havana's famous Nacional hotel. "Perhaps at the end of my stay."

The visit, which was kept under wraps until Richardson had landed, was the first sign that intensifying calls for the 62-year-old Gross' release might bear fruit after months of false hopes and bitter disappointment that have overwhelmed efforts at improved relations between the two Cold War enemies.

State Department spokeswoman Victoria Nuland said the Obama administration was aware of the trip and was in contact with Richardson.

"While Gov. Richardson is traveling as a private citizen, we certainly support his efforts to obtain Alan Gross' release," she said.

Gross has been jailed since his arrest in December 2009. Cuba says he was distributing satellite telephones and other communications equipment that are illegal to use without authorization. It has also called the USAID-funded democracy program that he was on a thinly veiled attempt at overthrowing the government.

Gross has said that he was only trying to help Cuba's tiny Jewish community improve Internet access, and that he had no desire to offend the country's communist government. In court testimony from March that was released last week by his own lawyer, Gross described himself as a "trusting fool."

"I was duped. I was used. And my family and I have paid dearly for this," the Maryland resident told the tribunal.

The court was apparently unmoved, convicting him of crimes against the Cuban state. The decision was later upheld by the nation's Supreme Court, leaving the American with no legal recourse.

That has led to growing appeals for Gross' release on humanitarian grounds. Those who have met and spoken with him say Gross has lost 100 pounds while in custody, and both his elderly mother and adult daughter are suffering from cancer, among other hardships the family has endured.

Richardson was last in Havana in August, when he met with Cuba's foreign minister and appealed for Gross's release. A former U.S. ambassador to the United Nations, Richardson has experience winning prisoner releases. As a congressman in 1996, he secured the liberation of three island political prisoners during talks with Fidel Castro in Havana.

Former U.S. President Jimmy Carter also raised Gross' case at the highest levels of government during a trip to Havana in March. The former president was received warmly by Fidel and Raul Castro and was even allowed to talk with Gross in jail, but he left empty handed.

Even before Gross was convicted, a senior State Department official said in January that she had received assurances from the Cuban government that he would soon be freed on humanitarian grounds. But optimism faded in recent months, as Cuban prosecutors sought and then won a stiff jail sentence against the American.

Gross' lawyer, Peter J. Kahn, said he welcomed Richardson's latest visit, which he said was undertaken at the invitation of Cuban authorities. He said he hoped it would lead to his client's freedom.

"We welcome any and all dialogue that ultimately will result in Alan's release," Kahn said in a statement on behalf of Gross' family. "We are grateful to Gov. Richardson for his continued efforts. We hope that the governor and Cuban authorities are able to find common ground that will allow us to be reunited as a family."

However, two senior Cuban officials said they were unaware of the trip.

"I know nothing about it," Parliament Chief Ricardo Alarcon, normally a leading voice on issues concerning the United States, told the AP.

Josefina Vidal, the Cuban Foreign Ministry's director of North American affairs, also said she had no information.

"I'm not up on that," she said.