HONG KONG (AP) — Hong Kong lawmakers gave final approval on Wednesday to a government proposal banning local ivory trading in the Chinese territory by 2021, with conservation groups hailing it as a major victory in the fight to save elephants.

Lawmakers overwhelmingly supported the measure, voting 49-4 to amend the existing law to outlaw sales of ivory in Hong Kong, which researchers say is the world's biggest retail ivory market.

The proposal also includes significantly stiffer penalties to deter smuggling of ivory and other highly endangered species.

Under the new law, the maximum sentence will increase to a 10 million Hong Kong dollar ($1.3 million) fine, double the current amount, and 10 years in prison, up from the current two years.

Wildlife activists applauded the move, even as Hong Kong moves more slowly than Beijing. Mainland China, the biggest source of global ivory demand, banned sales at the start of the year after shutting all carving factories and shops last March.

"A ban on ivory sales with heavier penalties in Hong Kong shows a clear commitment towards the future of African elephants," Cheryl Lo of the World Wildlife Fund said in a statement. "This will help reverse the trend of elephant poaching and illegal ivory trafficking."

The existing Hong Kong law allowed domestic sales of ivory dating from before CITES, or the Convention on International Trade in Endangered Species of Wild Fauna and Flora. Under CITES, ivory trading started to be regulated in the mid-1970s before a total ban in 1990 on international sales.

Activists say there are signs that unscrupulous dealers were exploiting that loophole to "launder" newer, illicit ivory, making Hong Kong a major black market trading hub.

They hailed the ban as a major step in efforts to slow the poaching that results in the annual slaughter of tens of thousands of elephants and threatens the lives of park rangers in Africa.

The Hong Kong government refused to offer any compensation to the city's dozens of ivory shop owners and hundreds of licensed traders, who had demanded tens of millions of dollars in return for giving up their ivory stockpile, estimated at 670 metric tons (740 short tons).

The new law will take effect in stages, with the full ban coming into effect at the end of 2021 after traders' current licenses expire.

Conservation groups, worried that Hong Kong's five-year enforcement gap with mainland China would fuel an increase in illegal trading, urged authorities to enforce regulations and step up monitoring.

WWF also called for governments in other Asian countries such as Vietnam, Laos, Cambodia and Japan to institute similar bans, saying there was evidence that those markets are increasingly catering to Chinese visitors.