* Stalemate over fate of president persists
* U.N. investigators arrive in Yemen
* Yemen says nine al Qaeda militants killed in Abyan
By Humeyra Pamuk and Mohammed Mokhashaf
DUBAI/ADEN, June 28 (Reuters) - Yemen is considering using force to secure and repair its main oil pipeline, blown up in an attack by angry tribesmen in mid-March, a senior Yemeni official told Reuters on Tuesday.
The comments came amid a persistent political impasse over the fate of President Ali Abdullah Saleh, who is recovering in Saudi Arabia from wounds suffered in a June 3 attack, and continuing unrest in the south, where nine Islamist militants were killed in fresh clashes.
The impoverished Arab state has been shaken to the core by months of protests against Saleh’s three-decade rule, a resurgent al Qaeda wing and a separatist rebellion in the south.
The Yemeni official said the government was in talks with tribesmen obstructing repairs of the Maarib oil pipeline.
“We’re close to reaching either a deal or a crackdown,” said the official, who declined to be named. “There is mediation, we have been in contact with them. But our patience is limited.”
The lack of crude has forced the Aden oil refinery to halt output, causing widespread fuel shortages and forcing the poorest Arab state to import more when it can least afford it.
The Yemeni government has blamed the opposition for the attack on the pipeline, which runs for 225 km (140 miles) from the Maarib oil fields in central Yemen to Aden in the south.
Saleh’s opponents say the president was behind the attack to show that his government was vital to provide services and stability in the country of 23 million.
The official declined to say when the government would start the repairs but said the decision would be made “very soon.”
“There is commitment and belief in the top level of the government that this situation can’t be sustained,” he said.
Yemeni officials have said the 69-year-old Saleh was expected to make his first public appearance since the palace attack as soon as Tuesday, but after a delay it remained unclear when that would be.
Previous announcements of Saleh’s imminent return have raised speculation about the condition of the president, who has not been seen in public since the attack, which killed at least seven people and wounded several top officials.
“Information on Saleh’s health is very scant,” said Khaled al-Dakheel, a Saudi political analyst. “His condition does not seem to allow him to appear on television, not to mention return home.”
The United States has been pressing Saleh to hand over power to his deputy, Abd-Rabbu Mansour Hadi, who has been acting president since Saleh flew to Riyadh earlier this month, under a Gulf Arab initiative that had been signed by opposition parties.
Hadi has resisted opposition calls for power to be fully transferred into his hands as a step towards early elections, insisting that Saleh was still the constitutional president.
Hadi met United Nations human rights investigators in Sanaa who had arrived on a mission to assess the situation in Yemen after months of unrest.
Underscoring chaos in the country, a military spokesman said the army killed nine Islamist militants associated with al Qaeda east of Zinjibar, capital of the volatile Abyan province.
The state news agency Saba quoted the spokesman as saying four other militants were injured in clashes in the area.
Saleh’s opponents say he is deliberately letting militants tighten their grip to prove that only he stands in the way of an Islamist takeover.
Separately, a Yemeni official said on Tuesday that three French aid workers kidnapped in Yemen in May were still alive.
“The security authorities are still looking for them,” Abdu al-Janadi, Yemen’s deputy information minister, told reporters.
“We can confirm that they are still alive and we hope those who abducted them will reconsider,” Janadi said, without giving details about the kidnappers.
The workers disappeared in the southeastern province of Hadramout. Yemeni and French authorities have previously said the three were probably kidnapped. In Paris, the French Foreign Ministry said it was checking the report. (Reporting by Humeyra Pamuk; additional reporting by Mohammed Mokhashaf in Aden and John Irish in Paris; Writing by Sami Aboudi; editing by Paul Taylor)