(Adds tougher checks on purchases of chemicals, para 5)
* Chinese authorities to sell buildings owned by exile leader
* Dozens of new reports of needle attacks
* Checks on purchases of chemicals
By Royston Chan
URUMQI, China, Sept 8 (Reuters) - Three buildings owned by the family of exiled Uighur leader Rebiya Kadeer in Urumqi will be demolished, Xinhua news agency said, as the Chinese government sought to reassert control over the ethnically-divided city.
The government ordered shops and businesses in central Urumqi to close early on Monday, giving rise to a wave of rumours of new unrest among citizens panicked by mysterious needle attacks.
Police received 77 new reports of needle attacks on Sunday and Monday, despite threatened punishments for both attackers and rumour-mongerers, Xinhua said. A Han Chinese crowd tried to beat up a Uighur on Monday after another alleged needle attack.
Streets were empty on Monday evening, under heavy security.
Xinhua, quoting the regional government, also reported that people buying "dangerous chemical products" in Xinjiang would face more stringent checks. The report gave no explanation for the tougher checks or link them to the unrest in Urumqi.
Thousands of Han Chinese protested in Urumqi last week, demanding the removal of regional party secretary Wang Lequan for failing to ensure their safety. Two other officials were sacked.
Last week's protesters also denounced the failure to proceed with trials for demonstrators charged after unrest on July 5, when 197 people died in rioting by Muslim Uighurs.
The Akida Trade Center, a building full of Uighur shops owned by the Akida Industry and Trade Co founded by Kadeer, were slated for demolition due to cracks in the walls and sunken footings, Xinhua said. The announcement confirmed a report on Aug. 19 by the Uyghur American Association.
More than 30 members of Kadeer's family, including siblings, children and grandchildren, had been living on upper floors of the building, the UAA said.
The Akida company building and the Tuanjie, or Unity, theatre, would also be torn down, Xinhua said. Those properties were also owned by Kadeer and her family.
China has repeatedly accused Kadeer, once a successful businesswoman, of triggering the deadly July unrest in the strategic and energy-rich northwestern region of Xinjiang.
At least two of Kadeer's sons who are still in China are in jail, while a daughter is under house arrest. Her oldest son manages her business interests in China. (Writing by Lucy Hornby; Editing by Ron Popeski)