RIYADH: Joining President Barack Obama for a condolence visit after the death of the King Abdullah, Mrs. Obama stepped off of Air Force One wearing long pants and a long, brightly coloured jacket — but no headscarf.

Under the kingdom's strict dress code for women, Saudi females are required to wear a headscarf and loose, black robes in public.

Most women in Saudi Arabia cover their hair and face with a niqab (veil). But covering one's head is not required for foreigners, and some Western women choose to forego the headscarf while in Saudi Arabia.

As an all-male delegation of dozens of Saudi officials greeted the Obamas in Riyadh, some shook hands with Mrs Obama. Others avoided a handshake but acknowledged the first lady with a nod as they passed by.

Saudi Arabia imposes many restrictions on women on the strict interpretation of Shariah law known as Wahhabism. Genders are strictly segregated and women are banned from driving, although there have been campaigns in recent years to lift that ban.

Guardianship laws also require women to get permission from a male relative to travel, get married, enroll in higher education or undergo certain surgical procedures.

More than 1,500 tweets criticised the first lady on Twitter using a hashtag that roughly translates to #MichelleObamaunveiled, said a report published on the Washington Post.

Some pointed out that Michelle Obama had worn a headscarf during a recent trip to Indonesia. However, many users said that Mrs Obama should not be criticised as the trip to Saudi Arabia was impromptu.

The Obamas' visit to Saudi Arabia itself stirred backlash due to recent international criticism of the country for the flogging of blogger Raif Badwani for insulting Islam. President Obama reportedly said that the visit was apolitical and he is not likely to discuss Badwani with the new king.

Some reports suggested that Saudi state television's broadcast blurred footage of Michelle Obama's head during the couple's meeting with Saudi Arabia's new king. However, Saudi Embassy officials in Washington denied that Michelle Obama's uncovered head was blurred on television, according to a report published on ABC News.

The broadcast showed Mr. and Mrs. Obama being welcomed by King Salman on a red-carpeted ramp and a military band played American and Saudi national anthems.