Yemen's acting leader has threatened to leave office unless outgoing President Ali Abdullah Saleh and his allies stop "interfering" in his duties, a senior member of the opposition said on Saturday.
The rift between Saleh and his deputy Abd-Rabbu Mansour Hadi is the latest obstacle to a Gulf-brokered plan to end months of protests and political deadlock that have paralysed the impoverished Arabian Peninsula state.
"Relations between Saleh and his deputy have deteriorated... and Hadi has informed Western mediators he will leave Sanaa if the interference in his jurisdiction continues," a senior member of the opposition Joint Meeting Parties (JMP) told Reuters on condition of anonymity.
Under a power transfer plan drawn up by Yemen's wealthier neighbours, the JMP and Saleh's General People's Congress party (GPC) divided up cabinet posts, forming a national unity government to steer the country towards a presidential election in February under Hadi's leadership.
Saleh signed that deal in November, having backed out of it three times beforehand, but question marks remain over the intentions of the veteran leader, who earlier this week said he would stay in Yemen, reversing a pledge to travel to the United States.
The JMP member said Hadi warned the mediators he would go to the southern port city of Aden and give up his position if Saleh and his followers continued to hinder him, adding that their differences had led him to boycott a recent meeting.
"Extremists in the Congress party headed by Saleh harshly criticised the deputy president in a meeting attended by the president, which made the deputy boycott the last meeting that president Saleh convened with the leaders of his party and his ministers," said the JMP member.
Relations between Saleh and his deputy soured after Hadi refused the president's orders to restore his allies to jobs from which they were ousted by protesting workers, the JMP figure said.
More than a month after the Gulf deal was clinched, Yemenis angry at its offer of immunity from prosecution for Saleh over the killing of demonstrators by security forces are still taking to the streets, calling for him to be put on trial.
United Nations High Commissioner for Human Rights Navi Pillay said on Friday any guarantee of immunity to Saleh would violate international law, undermining the Gulf initiative.
In the south of the country, where central government control has been weakened by the political upheaval in Sanaa, militants halted a march by thousands of Yemenis trying to return to their homes, which they fled due to fighting between the army and Islamist fighters suspected of links to al Qaeda.
The United States and Saudi Arabia, both targets of al Qaeda, fear a power vacuum in Yemen is giving militants space to thrive alongside a key shipping strait.
Marchers said they were stopped around 10 km short of the city of Zinjibar by militants who told them they could not pass because the area was mined.
"We will not despair. We will try a second time and a third time and a fourth until we can enter and go back to our houses and our city. The militants must understand they are not wanted," said one marcher, Saleh al-Mosalli.