* Islamists block aid at gates of Timbuktu
* Talks to release convoy unresolved
* Northern Mali in chaos since coup, rebellion
TIMBUKTU, May 15 (Reuters) - Mali's Islamist rebel group Ansar Dine blocked an aid convoy with tonnes of food and medical supplies for the northern city of Timbuktu on Tuesday, objecting to the presence of women in a reception committee set up for the aid.
The convoy marked the first aid deployed to Timbuktu since Mali's government lost control of the vast northern region to separatist and Islamist rebels who capitalised on a March 22 coup in the capital Bamako to make a swift advance.
Tens of thousands of people have fled Mali's north since the rebel advance, many of them for neighbouring Niger, Burkina Faso and Mauritania. Those remaining face widespread lawlessness and worsening shortages of food and medicine in a zone that is also entering one of the Sahel region's recurrent droughts.
"We don't appreciate that we, as the authority in Timbuktu, were not consulted in organising the reception and distribution of this humantarian convoy," Sanda Ould Boumana, a spokesman for the Ansar Dine group seeking to impose Islamic sharia law, said.
Among the group's objections was a plan by a local committee of Timbuktu residents to hold a welcoming ceremony for the aid convoy that included women. Talks to release the convoy have so far failed, Boumana told accompanying reporters.
A Reuters reporter said the convoy, which reached the city gates late on Monday after a three-day trip from Bamako, was now surrounded by heavily armed Ansar Dine gunmen in pick-up trucks.
People in the convoy, including doctors, aid workers and journalists, were allowed into the city.
Ansar Dine, which has loose links with local al Qaeda factions, has already sought to impose sharia in parts of the rebel-controlled north, including in regional centres Gao and Kidal. Its militants attacked and burned a sacred tomb in Timbuktu, a UNESCO World Heritage Site, earlier this month, alleging such shrines were un-Islamic.
"This is a cry for help from a city entitled to protection, rescue and preservation, if indeed the words 'World Heritage Site' are not empty," a group of local artists and intellectuals said in a statement issued Tuesday.
In Gao on Tuesday, local youths took to the streets for the second straight day to protest rebel control of the town, shouting "Down with Ansar Dine and MNLA". MNLA is the name of the Tuareg rebel group also vying for control of the north.
Residents of Gao said Ansar Dine had outlawed video games, western and Malian music, soccer and bars.
A refugee camp for about 750 residents of northern Mali - most of them children - has been set up near Mopti, about halfway between Bamako and Timbuktu.
"We can't complain about the conditions here, and we feel safer here than we did at home," said Boubacar Traore, a man in his fifties who fled Hombri in April. "But we are waiting for peace to return so that we can live like before," he said.
(Reporting by Cheikh Diouara and Adama Diarra; Writing by Richard Valdmanis; Editing by Louise Ireland)