An international rights group urged the United States, where Yemen's outgoing President Ali Abdullah Saleh is staying, to probe his forces' deadly crackdown on opponents during a year-long uprising.
"The United States has an obligation to investigate the serious and credible allegations of torture and other widespread violations brought against Saleh," the International Federation for Human Rights (FIDH) said in a statement late Tuesday.
Saleh, who gave up power in return for immunity from prosecution based on a Gulf-brokered deal he signed in November, has been in the United States since January 29 for treatment of burn wounds he suffered when his presidential palace was attacked in June.
The deal came following months of demonstrations in which hundreds were killed in a crackdown by Saleh's loyalists and forces across the country.
"The United States has failed to comply with its legal responsibilities to uphold this resolution and has allowed Saleh to remain in the United States without legal consequence while demonstrations calling for justice continue on a daily basis in Yemen," said the Paris-based FIDH.
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The group "and its partners in Yemen... call on the US government to uphold its international responsibilities and open an investigation into torture against Saleh," it added.
Yemen's parliament last month adopted a law giving Saleh "complete" immunity from prosecution in return for stepping down under the transition deal.
Rights groups have repeatedly pressed the United States to prosecute Saleh.
In a report this month based on witness accounts, Human Rights Watch said that Saleh's forces had stormed and shelled hospitals, evicted patients at gunpoint and beat medics during an assault last year against protests in the city of Taez.
The New York-based rights group said that at least 120 people died in Taez, of whom 57 were taking part in peaceful demonstrations and 22 were children.
Yemenis on Tuesday voted in a referendum-like presidential poll in which Vice President Abdrabuh Mansur Hadi stood as sole candidate to lead the country during a two-year interim period, based on the transition deal.
State Department spokeswoman Victoria Nuland said Tuesday that Saleh was in California and would enjoy diplomatic immunity until Hadi was inaugurated.