China needs to better regulate foreign non-governmental organizations (NGO) operating in the country for national security reasons, an official said on Wednesday, as the government drafts a law that has unnerved many aid groups.

Fu Ying, spokeswoman for China's largely rubber-stamp parliament, said she understood there were more than 6,000 foreign NGOs operating in the country, who had brought with them money, expertise and technology.

"They have been beneficial for our development and have made contributions, but there are some deficiencies in their management," she told a news conference, a day ahead of the opening of parliament's annual meeting.

China needed a law to better regulate them to ensure they had "sufficient legal basis" to operate in China, Fu said.

"On the one hand, we need to protect their legitimate interests, to let them play an even greater role, and on the other hand they need even more effective management, to sufficiently protect our country's security and social stability."

China began an investigation into the operations of NGOs last year, to prepare for tighter regulations, as part of a security drive ordered by a new national panel headed by President Xi Jinping.

The southern city of Guangzhou put in place a regulation in November to regulate NGOs with foreign funding, sparking fear among non-profit workers in the area of a crackdown.

The bill being considered requires overseas NGOs to register with, and be approved by, authorities if they want to set up representative offices or operate temporarily, according to state media.

It is not clear when the law could come into effect.

NGOs have mushroomed in China in recent years, and can have a confrontational relationship with the government, especially if they work with sensitive groups such as sex workers or drug addicts.

Many foreign NGOs also operate, though they have traditionally registered as businesses as the approval process is easier. Authorities have treated some with suspicion, worried they may try and spread foreign values.

While the government requires all NGOs to register, the process is often difficult, driving many Chinese and foreign NGOs to operate without proper authorization.

The national security commission was unveiled in 2013, and helps Xi's administration coordinate responses to domestic and foreign security issues, including social unrest.

Xi's government has launched a sweeping crackdown on freedom of expression and association since coming to power last year, including the jailing of anti-corruption activists who have pushed for officials to disclose their assets.