Kazakhstan on Wednesday extended a state of emergency to January 31 in the Caspian Sea town of Zhanaozen where 16 people died last month in clashes between striking oil workers and police. "I resolve to extend the state of emergency in the town of Zhanaozen in the Mangistau region ... until 7 am on January 31," strongman President Nursultan Nazarbayev said in a decree posted on his official website. The clashes, which came after months of strikes in Kazakhstan's energy-rich Caspian Sea region, coincided with celebrations for the 20th anniversary of the country's independence and were the deadliest in its post-Soviet history. The state of emergency, introduced after the December 16 protest had been due to run out on Thursday, but Nazarbayev did not give a reason for its extension. Under the state of emergency, protests are banned and there is a curfew in place. The unrest -- which has severely damaged Kazakhstan's reputation among investors as an oasis of stability in turbulent Central Asia -- has also forced a shake-up of some of its most senior political and economic figures. Nazarbayev last month fired his son-in-law Timur Kulibayev, seen as a possible successor, as head of the vast Samruk-Kazyna holding firm which has stakes in the companies whose workers were striking. Kazakhstan also announced the sacking of the governor of the Mangistau region, where the clashes took place, as well as the board chairman of state-controlled energy firm Kazmunaigaz, Bolat Akchulakov. Nazarbayev, who critics said was initially slow to react to the riots, has accused the energy bosses of bearing responsibility for failing to resolve the labour disputes.