KANDAHAR, Afghanistan (Reuters) - The acting police chief of southern Afghan province was shot and killed by a fellow officer, about a month after his predecessor was also assassinated, authorities said Sunday.

The death of the second police chief for Uruzgan province to be killed in six weeks appeared to be an insider attack, but it was unclear what motivated the junior police officer to open fire.

"The acting police chief, Gulab Khan, was in a meeting with a friend late last night when his colleague opened fire and killed both of them," provincial governor Amanullah Timori told Reuters.

"The policeman is detained and an investigation is ongoing."

The arrested officer was a member of the criminal investigation department in Uruzgan.

Gulab Khan had been acting police chief since his powerful predecessor, Matiullah Khan, was killed in a suicide attack while visiting the Afghan capital Kabul in mid-March.

Taliban insurgents claimed responsibility for the attack on Matihullah Khan.

On Sunday, Taliban spokesman for southern Afghanistan Qari Yousef Ahmadi, declined to comment on the Uruzgan shooting, saying he was still gathering information.

The Taliban have sometimes claimed that insider attacks reflect their ability to infiltrate the enemy, but Afghan and collation forces say incidents more often arise over misunderstandings or arguments.

An Afghan soldier opened fire on U.S. soldiers in eastern Nangarhar province in early April, killing one American. The shooter himself was also killed and two Afghan soldiers were wounded in the shootout.

(Writing by Mirwais Harooni; Editing by Michael Perry)