US President Donald Trump's daughter Ivanka said Sunday that ultra-conservative Saudi Arabia has made “encouraging” progress in empowering women but more freedom is needed.

“Saudi Arabia's progress, especially in recent years, is very encouraging,” Trump's eldest daughter told a group of Saudi women she met in Riyadh while accompanying her father on a visit to the Muslim kingdom.

“But there's still a lot of work to be done and freedoms and opportunities to continue to fight for,” added Ivanka, who serves as an advisor to her father.

“Around the world, women continue to achieve unprecedented levels of rights and freedoms. Today you all stand on the frontlines of the fight for gender equality,” she told a roundtable of women led by Princess Reema bint Bandar, deputy president of the Women's Sports Authority.

Saudi Arabia imposes many restrictions on women.

It is the only country where they are not allowed to drive. When in public, women in Saudi Arabia are expected to cover from head to toe.

Riyadh has pledged a programme of social and economic reforms as part of the ambitious “Vision 2030” strategy launched last year.

A royal decree earlier this month reportedly stipulated that women are no longer required to obtain a male guardian's consent to carry out certain activities.

In February, a Saudi woman was appointed to head the Saudi stock exchange, Tadawul, while another was appointed as head of the major bank Samba.

“The stories of Saudi women, such as yourselves, catalysing change, inspire me to believe in the possibility of global women's empowerment,” said Ivanka.