First lady Melania Trump and the oldest child of President Donald Trump, Ivanka, on Sunday created controversy in the US when they refused to wear headscarves in Saudi Arabia.

Interestingly, Trump had criticised former first lady Michelle Obama for failing to wear the head covering when she visited the Arab nation in 2015, Efe reported.

Melania and Ivanka are accompanying Trump on his first international trip as president, arriving in Riyadh on Saturday, the first stop on a journey that will take him to Israel, The Vatican and to NATO and G7 summits in Brussels and Sicily, respectively.

The first lady and Ivanka on Saturday appeared at several official events in the Saudi capital with uncovered heads, although they did conform to the conservative kingdom's accepted modesty norms by wearing sober outfits consisting of loose-fitting pantsuits with long-sleeved blouses in dark colours.

According to the Saudi kingdom's strict dress code, Saudi women who go out in public must wear the "abaya," a loose over-garment or robe, and many also hide their hair by wearing the "hijab," or Islamic headscarf.

However, it is normal for foreign women visiting the Arab country as part of international delegations not to cover their heads.

For instance, British Prime Minister Theresa May and German Chancellor Angela Merkel did not wear headscarves during their separate visits to Saudi Arabia earlier this year, and Secretary of State Hillary Clinton did not cover her head on her several trips to the kingdom.

"Many people are saying it was wonderful that Mrs. Obama refused to wear a scarf in Saudi Arabia, but they were insulted. We have enuf enemies," tweeted Trump on January 29, 2015, using a common social network abbreviation for the word "enough."

On the other hand, some Republican politicians, including Senator Ted Cruz, at the time applauded Michelle Obama for her choice.

When asked about why Melania and Ivanka opted not to cover their heads in Saudi Arabia, the White House said that there was no requirement to wear such coverings, CNN reported.

On his first day in Riyadh, Trump was warmly welcomed and feted by the 81-year-old Saudi king, Salman bin Abdulaziz.

The US and Saudi Arabia on Saturday signed a series of accords in various areas valued at $380 billion over the next 10 years.