A prosecutor in Argentina has accepted a request to prosecute Mohammed bin Salman for alleged crimes against humanity, hours after the Saudi Arabia crown prince arrived in the country for the G20 summit.

It is highly unlikely that such a prosecution could be successfully launched before the prince leaves Buenos Aires, but the move is an embarrassing development as world leaders gather for the two-day summit, which begins on Friday.

The advocacy group Human Rights Watch presented a writ earlier this week, arguing that Argentinian authorities should invoke universal jurisdiction laws to seek prosecution of the prince for mass civilian casualties caused by the Saudi-led coalition’s campaign in Yemen, and for the torture of Saudi citizens – including Jamal Khashoggi, who was killed in the Saudi consulate in Istanbul.

On Wednesday a source said that the court had accepted the writ, and a prosecutor had asked a judge to determine if either Saudi Arabia or Yemen are investigating the prince for possible crimes against humanity. If no cases have been opened in either country, HRW argues that the principle of universal jurisdiction could apply.

Before that could happen, however, the supreme court would have to rule whether Prince Mohammed is covered by diplomatic immunity – a decision which would be unlikely to come before the prince leaves the country after the G20 finishes on Saturday.

The centre-right government of Mauricio Macri has said it is not concerned by the legal manoeuvres. “We don’t believe the Human Rights Watch writ will prosper,” said a spokesperson for the foreign minister, Jorge Faurie, who greeted the prince at the airport Wednesday.

“Mohammed bin Salman is protected by diplomatic immunity and he is also travelling in his official status as representative of a foreign head of state. Besides, cases involving diplomatic immunity can only be decided by the supreme court and his visit will be too brief for it to reach the court. The case is in the hands of the court and the government will not interfere with it,” the spokesperson said.

Kenneth Roth, HRW’s executive director, said: “The Argentine judiciary, by taking steps toward a formal investigation, is sending a clear message that even powerful officials like Mohammed bin Salman are not above the law and will be scrutinized if implicated in grave international crimes.

“A cloud of suspicion will loom over him as he tries to rebuild his shattered reputation at the G20, and world leaders would do well to think twice before posing for pictures next to someone who may come under investigation for war crimes and torture.”