A new law has come into force in China, tightening control over foreign not-for-profit organisations operating inside the country.

The law, which was announced last April, provides what the government says are long overdue reforms to regulate the activities of the thousands of NGOs operating in China.

The new regulation bans political or religious activities at odds with the Chinese government. It also states that NGOs must not undermine or damage China's national interests.

Coming at the end of a year that has seen a crackdown on human rights lawyers and other activists in China, critics of the new law say it will lead to an erosion of civil society.

Critics believe it has been left deliberately vague so the nation can interpret it any way it wants.

Activists also see it as a further attempt by President Xi Jinping to strengthen his grip on power.

"What Xi Jinping wants to do, most likely, is take the NGO space, which was kind of operating in a grey area, and make it fully come on board, so the government can see and control everything," William Nee of Amnesty International told Al Jazeera.