About 20,000 people have taken to the streets of Hong Kong in one of the biggest demonstrations in recent years to protest against planned anti-subversion legislation.

The protest snaking through the streets of Hong Kong to the territory's government headquarters was far larger than most people had expected.

I don't want Hong Kong to become like China Protester

BBC correspondent Damian Grammaticas says the new laws are the most controversial issue to confront Hong Kong since the territory was returned to China five years ago.

When Hong Kong was returned from British to Chinese sovereignty in July 1997, the government was required to outlaw subversion, sedition, treason and other crimes against the Chinese state.

Protesters say freedom of speech will be muzzled

Our correspondent says the proposals put forward by the Hong Kong government, with backing from Beijing, are far-reaching and are starting to arouse deep-seated opposition.

People found guilty under the new law can be imprisoned for life.

But critics say the law is so loosely written it would let the authorities trample on people's freedoms or ban groups the government does not like.

Guaranteed freedom

"I don't want Hong Kong to become like China," said a 48-year-old civil servant who joined Sunday's demonstration.

Another protester, a 25-year-old bank clerk added: "The rights we have are not guaranteed in the future."

But the Hong Kong Security Bureau said the rally bore testimony to the freedom of expression and the right to demonstrate enjoyed by the territory's residents.

"These rights and freedoms are guaranteed," the bureau said in a statement.

Demonstrations in favour of the new law took place on Wednesday

Police put the number of protesters at 12,000, while organisers said 50,000 had turned out. Reports say the demonstration stretched for six kilometres (3.5 miles)

Pro-democracy politicians and human rights activists have been joined by businessmen who fear the legislation could damage Hong Kong's role as a business centre because it might limit the exchange of financial information.

Wealthy newspaper publisher Jimmy Lai, who joined the marchers on Sunday, said the law was like "an invisible, tightening collar".

Members of the Falun Gong spiritual movement - which is banned in mainland China - participated in the march.

Christian groups began Sunday's march with a prayer session at the departure point at Hong Kong's sprawling Victoria Park.