King Abdullah and Crown Prince Sultan flanked by 40 women in abayas but mostly with their faces bare

King Abdullah of Saudi Arabia is not normally associated with radical moves but the 85-year-old monarch is making waves with signals encouraging greater tolerance of women's rights.

In recent days Abdullah's appearance in an unusual group photograph has become a talking point across his realm and the wider Arab world. The king and his brother Crown Prince Sultan were flanked by 40 women dressed in modest abayas but mostly with their faces bare, a novelty that is seen as evidence of rare liberalism at the top.

The king's pose, at a conference in the southern city of Najran last month, is big news because it appears to challenge the norm in a country where unrelated men and women are kept strictly apart, women are covered from head to toe and alcohol and women's driving are banned. Under Saudi law a woman must not leave home without a male "guardian" (her father, husband or brother) to whom she is legally subordinated.

"I think this is a great picture and everyone is talking about it," said Dr Maha Muneef, a prominent physician and government adviser. "This is a picture that sent a message that it is OK to work with women ... and that there's nothing wrong with that."

Overzealous enforcement by the Commission for the Promotion of Virtue and Prevention of Vice – the morality police – is routinely criticised by liberals. Saudi and foreign observers detected royal intervention when the commission suddenly reversed a decision to sack Sheikh Ahmad al-Ghamdi, its head for the Mecca region, after he questioned whether Islam in fact required gender segregration.

Ghamdi's swift reinstatement was widely interpreted as a vote of confidence by the palace in reformist ideas. The presence of the crown prince in the group photograph, which was distributed to selected media by the palace, suggested a pointer to future policies.

There have been other signs that the Custodian of the Two Holy Mosques, to use Abdullah's full title, is challenging the ultra-conservative Wahhabi religious establishment that has ruled in tandem with the House of Saud since the modern kingdom was created in the 1920s.

Last autumn he sacked a senior cleric who demanded that religious scholars vet the curriculum at the new $10bn co-educational international science university near the Red Sea city of Jeddah. Shortly before that he appointed Noura al-Faiz as the country's first woman deputy cabinet minister, although the limits of her position were quickly underlined when PR officials removed her image from a group photograph taken with her male boss.

Analysts warn that opposition to these sorts of changes should not be underestimated. In February Sheikh Abdul-Rahman al-Barrak, another hardline independent cleric, issued a fatwa calling for opponents of gender segregation to be killed if they refused to abandon their ideas.

"Anyone who accepts that his daughter, sister or wife works with men or attends mixed-gender schooling cares little about his honour and this is a type of pimping," he said. This week Barrak drew fire from a Riyadh judge, Sheikh Issa al-Ghaith, who accused him of "raising discord" and "inciting brother against brother".

Speculation is mounting that there will be more substantial changes, including the prospect that women may be allowed to drive. Sceptics insist they need to see substance.

"There are some good signs but we need to see women lawyers in court and women driving if the changes are to be real and tangible," said Mai Yamani, an independent Saudi scholar. "Having pictures of women with the king is very nice, but if you compare Saudi Arabia even with the other Gulf countries this is still all very timid."