The rose-colored sandstone of Madain Saleh, a UNESCO World Heritage site, near Saudi Arabia's northwestern town of al-Ula Photo: AFP

Saudi Arabia on Friday said it was offering tourist visas for the first time, opening up the ultra-conservative Islamic kingdom to holidaymakers as part of a push to diversify its economy away from oil.

The kingdom also eased its strict dress code for foreign women, allowing them to go without the body-shrouding abaya robe that is still mandatory public wear for Saudi women, as authorities open up one of the last frontiers of global tourism.

"We make history" today, tourism chief Ahmed al-Khateeb said before an official gala to mark the launch in Diriyah, a historical site near Riyadh.

"For the first time, we are opening our country to tourists from all over the world."

Citizens from 49 countries are eligible for online e-visas or visas on arrival, including the US, Australia and several European nations, the statement said.

Kickstarting tourism is one of the centerpieces of Crown Prince Mohammed bin Salman's Vision 2030 reform program to prepare the biggest Arab economy for a post-oil era.

Tourism authorities have repeatedly said that Saudi Arabia will not permit alcohol.

But Khateeb said there will be no restrictions on unaccompanied foreign women, who will also not be obliged to publicly wear an abaya although they will be expected to dress modestly.

Men and women must avoid "tight fitting clothing" or clothes with "profane language or images", read an instruction on an English language website launched by the tourism authority.

"Women should cover shoulders and knees in public," it said.

Visas in the desert kingdom, endowed with rich bedouin heritage and archaeological sites, had until now been restricted to expat workers, their dependents and the Muslim pilgrims travelling to Islam's holiest sites. 

Riyadh last year began issuing temporary visas to visitors to attend sporting and cultural events.

In an effort to change perceptions, Prince Mohammed has relaxed some of the kingdom's most rigid rules - lifting a ban on cinemas and women drivers while allowing gender-mixed concerts and sporting extravaganzas.

"Saudi Arabia is opening. We are opening our economy. We are opening our society," Khateeb said.

Lacking the infrastructure to accommodate visitors, Saudi Arabia has splurged billions in an attempt to build a tourism industry from scratch.