Vatican City (AFP) - The Vatican on Monday offered to help the United States in its efforts to close Guantanamo prison, a goal fervently supported by Pope Francis.

The offer came during talks between the pontiff's Secretary of State, Pietro Parolin, the number two in the Vatican hierarchy, and John Kerry, the US Secretary of State.

Vatican spokesman Federico Lombardi said the Holy See welcomed recent signs President Barack Obama appears to have accelerated efforts to close the controversial facility where some detainees have been held for more than a decade without charge and tortured.

He said the Vatican stood ready to "help find adequate humanitarian solutions through our international contacts" in order to help place detainees, adding that Parolin and Kerry had discussed the issue in depth.

Obama came to power six years ago promising to close Guantanamo, but has been frustrated in his efforts by a combination of opposition from Congress and the difficulties involved in finding homes for prisoners who are often unwanted by their home states and/or suspected of involvement in terrorist actions, including the September 11, 2001, attacks in some cases.

The pope made clear his feelings on the kind of abuses associated with Guantanamo in October, when he railed against the "penal populism" that led to countries facilitating torture, using the death penalty and incarcerating people without trial.

"These abuses will only stop if the international community firmly commits to recognising... the principle of placing human dignity above all else," he said.

Six prisoners -- four Syrians, a Palestinian and a Tunisian -- left Guantanamo earlier this month for Uruguay after 13 years of detention. That left 136 still incarcerated, 67 of whom had been cleared for release by the US administration.

Of that group, 54 are Yemenis who cannot go home because of the country's chaotic current state.

Of the men who have not been cleared for release, some 15 are classified as "high value" detainees currently considered too dangerous to be tried or incarcerated in the United States.

For Guantanamo to be closed, Obama will have to persuade Congress to accept the transfer of this group to US facilities, which currently looks unlikely according to most observers of the US political scene.

Kerry was in Rome for talks with Israeli Prime Minister Benjamin Netanyahu as part of an effort to relaunch a peace process in the Middle East. The Vatican spokesman said Francis welcomed the US efforts on that score.