"France is potentially an accomplice to serious violations of humanitarian laws by selling weapons and military equipment to Saudi Arabia, given what we know is taking place in Yemen," said Aurelie Perrier, coordinator for Yemen and Saudi Arabia at Amnesty International France.

"We want to ask President Macron to stop arms transfers to Saudi Arabia and to lift the blockade on Yemen," she told AFP at a protest under the Eiffel Tower as Prince Mohammed kicked off his visit to Paris.

Two other groups, the Weapons Observatory (Obsarm) and the International Federation for Human Rights (FIDH), said the sheer volume of French weapons exports to Saudi pointed to the likelihood that they have been deployed in Yemen.

The groups said French exports included types of equipment reported to have been used in Yemen, including Leclerc tanks and Caesar howitzers, while "confidential testimony" also pointed to the presence of French arms on the ground.

"If these indicators do not constitute proof, they throw serious suspicion on the massive presence and use of French military equipment in Yemen," they said in a statement.

A Saudi-led coalition has been bombing and blockading Yemen since 2015 in a conflict that has left 10,000 people dead.

A combination of fighting, disease and food shortages has led the Unirws Nations to call it the world's worst humanitarian crisis.

Prime Minister Edouard Philippe's office insisted last month that French land weapons sold to Riyadh were "defensive" and being used in Saudi Arabia to deter cross-border attacks.

He added that "surveillance measures" to track the use of French weapons had been "strongly reinforced in recent months".

Government spokesman Benjamin Griveaux said Monday there was a "clear interest for French industry" in continuing arms exports to Riyadh.

"It's an important part of our diplomacy," he said, while adding: "That doesn't mean turning a blind eye."

- Human rights concerns -

As the 32-year-old crown prince continues an international charm offensive that has included stops in the United States, Britain and Egypt, rights groups urged Macron to pressure his guest on human rights violations.

"Saudi Arabia remains one of the worst countries in the world in terms of its human rights record," Perrier said.

The prince has used his tour to project his reforms -- including the historic lifting of a ban on women driving, the revival of cinemas and tolerance for mixed-gender concerts -- as part of his pledge to return the kingdom to moderate Islam.

Prince Mohammed "considers himself a revolutionary, but if so, then he has to end the institutionalised oppression that has continued to build even after he came to power," said Amnesty France director Sylvie Brigot-Vilain.

"Especially regarding voices that oppose the regime, who increasingly find themselves behind bars."