The US authorities announced a near-total ban on the trade of African elephant ivory on Thursday, finalizing a years-long push to protect the endangered animals.

Conservation groups welcomed the move, which aims to reduce the slaughter of more than 35,000 of Africa's 450,000 elephants estimated to be killed each year, mainly for ivory.

"Today's bold action underscores the United States' leadership and commitment to ending the scourge of elephant poaching and the tragic impact it's having on wild populations," Secretary of the Interior Sally Jewell said.

But the move to restrict the African ivory market in the United States -- the world's second-largest consumer of illegal ivory after China -- comes with notable exemptions, including for documented antiques.

The final rule, which takes effect July 6, "substantially limits" imports, exports and sales of such ivory across state lines, the US Fish and Wildlife Service (FWS) said.

While prohibiting most commerce, it does make exceptions for some "pre-existing manufactured" items, including musical instruments, furniture and firearms that contain less than 200 grams of ivory and meet other specific criteria, according to the FWS statement announcing the rule.

Antiques, as defined under the Endangered Species Act (ESA), are also exempt. "Antique" items are at least 100 years old and meet several additional requirements.

Under Thursday's final rule, the import of sport-hunted trophies is limited to two per year.

People will also be allowed to keep lawfully acquired ivory and are not banned from donating, giving away or receiving ivory as a gift "provided it was lawfully acquired and there is no exchange for other goods or services involved," the FWS said.

"Limited exceptions" to the ban on import and export of African elephant ivory will also apply to items that are part of a traveling exhibition or "are part of a household move or inheritance when specific criteria are met" as well as "ivory for law enforcement or genuine scientific purposes," the rule said.

- 'Blood ivory' -

The new measures fulfill restrictions in an executive order on combating wildlife trafficking President Barack Obama issued in 2013, the FWS said.

Once illegal ivory enters the market, it becomes virtually impossible to tell apart from legal ivory, it said, adding that demand for elephant ivory, particularly in Asia, "is so great that it grossly outstrips the legal supply and creates a void in the marketplace that ivory traffickers are eager to fill."

The outlawed ivory trade is mostly fueled by demand in Asia and the Middle East, where elephant tusks and rhino horns are used in traditional medicine and for ornaments.

"We hope other nations will act quickly and decisively to stop the flow of blood ivory by implementing similar regulations, which are crucial to ensuring our grandchildren and their children know these iconic species," Jewell said.

The Wildlife Conservation Society (WCS) welcomed the final rule, calling it historic and groundbreaking.

"The USA is boldly saying to ivory poachers: You are officially out of business," WCS president and chief executive Cristian Samper -- a member of an Obama task force on wildlife trafficking -- said in a statement.

Patrick Bergin, chief executive of the US-based African Wildlife Foundation (AWF), also praised the move.

"Strong laws around wildlife crime and strong enforcement of those laws are absolutely critical in deterring traffickers and poachers," he told AFP.

"All countries -- and especially those that are source, transit or destination countries for illegal wildlife products -- have a role to play in tidying their own house."