Donald Trump Jr's secretive Mongolia hunting trip cost $60K more than first disclosed

How much does it cost US taxpayers for one of Donald Trump's sons to hunt an endangered sheep in Asia and stop for a secretive meeting with the president of Mongolia? Sixty-thousand dollars more than initially disclosed, according to a government watchdog group.

Donald Trump Jr, the president's oldest son, visited the country last year on a hunting vacation organised by a company owned by a member of the Mongolian president's political party. It was that company that helped Don Jr obtain a hunting permit for the argali sheep -- after he already had killed one of the animal.

US Secret Service documents initially put the cost of the trip at around $17,000. But Citizens for Responsibility and Ethics (CREW), a Washington-based government watchdog organisation, obtained additional documents that put the actual costs of the trip for US taxpayers at over $75,000.

The initial documents did not cover his stop in Ulaanbaatar to meet with Khaltmaagiin Battulga, Mongolia's president, or his flight costs, CREW found.

The White House, Trump campaign and the Trump family business each have never released details of his meeting with the Mongolian leader, even though taxpayers funded at least part of the stop.

Family members of all presidents receive US government protection, especially on foreign travel. One reason why is a sitting president could be forced into certain actions that may be counter to US interests in order to retrieve or keep a family member safe.

"As a son of the president, Donald Trump Jr is entitled to Secret Service protection and should be protected," CREW wrote in a statement. "But taxpayers deserve to know how much they are paying to facilitate his trophy hunting and interactions with major political donors and foreign leaders."

The watchdog group found the Trump family is outpacing the Obamas on protected trips by an order of 12.

"While we know that many of those trips have been to promote or support Trump Organisation business, there are thousands of trips that remain a mystery," CREW said. "With tens of millions of dollars of taxpayer money spent protecting the Trump family, the Secret Service has run out of money and Congress has had to dramatically increase the agency's budget."

Don Jr has solidified himself as a big presence in the movement that put his father in the White House, and is a regular speaker at his father's political rallies. He typically delivers a slightly toned-down, and more organised, version of the president's wide-ranging hybrid speech-monologue of ad libs.

But his spiel, which typically comes shortly before his father hits the stage, gets the crowd revved up as Don Jr bashes Democrats, warns about "socialism" and touts his father's record