The Donald Trump administration issued two authorisations for the transfer of technical "nuclear expertise" to Saudi Arabia after the murder of journalist Jamal Khashoggi late last year, US Senator Tim Kaine has revealed.

Kaine, a Democrat from Virginia, where Khashoggi resided, called the decision "shocking" - as it came amid global outrage over the Saudi journalist's gruesome murder on 2 October.

The two approvals were issued on 18 October - only 16 days after Khashoggi was killed - and on 18 February, respectively.

Known as "Part 810 authorisations", they allow US companies to discuss and work on nuclear-related projects in the Gulf kingdom.

"I have serious questions about whether any decisions on nuclear transfers were made based on the Trump family's financial ties rather than the interests of the American people," Kaine said in a statement on Tuesday.