The model adjusts her clothing, stares at the camera with a hint of a smile, holds her head high and the photographer starts snapping.

But at this photoshoot on the Asian side of Istanbul, the models, impeccably made up, sport no body-hugging Western styles.

All wear headscarves and loose fitting outfits in a shoot for one of the industry's fast growing sectors - modest but trendy Islamic fashion.

Istanbul is positioning itself to be a hub in this nascent industry, which according to the Dubai-based Islamic Fashion and Design Council could be worth almost $500 billion within decades.

Modanisa, a Turkish online Muslim clothing retailer, started small in 2011 and today is one of the biggest names in the market. It offers more than 30,000 products - from casual tunics to shiny evening wear to sports gear, shoes and accessories - from 300 brands and ships to 75 countries.

The firm calls itself the "first online fashion and shopping website for women who embrace a modest dressing style".

Modanisa's CEO Kerim Türe said that in years past there was so little choice that a religiously conservative young woman had no option but to wear the same clothes as her mother.

"If that was happening in a country (Turkey) where 99 percent of its population is Muslim, we wondered how the situation was around the world," he added. "That's how we've started our worldwide web business."

He was surprised by this summer's furor in strictly secular France over whether Muslim women had the right to wear the burkini swimsuit, which covers all but the hands, feet and face.

'We are the same as you'

French courts ultimately ruled that a burkini ban by some 30 towns was "clearly illegal" and a violation of fundamental rights.

For Türe, the burkini is not a symbol but a choice. "I barely understand how a country, one of whose main pillars is freedom, can oppose the Muslim swimsuit," he said.

His firm's catalogue offers a range of "fully closed swimsuits" starting at 40 euros ($45), and, ironically, its burkini sales jumped during the debate by 15 to 20 percent to France itself and 30 percent to the Netherlands.

In May, Istanbul hosted its first conservative fashion week at the historic Haydarpaşa train station to showcase this rapidly growing market.

It was organized by Franka Soeria from Indonesia, another center for Islamic clothing.

As a global consultant on modest fashion trends, she decided three-and-a-half years ago to move to Istanbul - whose position straddling Europe and Asia, some say, gives it an edge.

The point of offering stylish modest clothing was not to tell people to cover up but to show that "we are also the same as you ... we don't want to be excluded, we don't want to look different," she said, wearing an elegant black hijab.

"We are showing that, hey, I am modest, I like to cover. I also like fashion. This is just my style. Just accept," Soeria said.

Osman Özdemir, a Turkish designer of modest fashion, is the in-house designer for Modanisa but is now also working for several other firms.

"I believe Istanbul will be trend-setting on Islamic fashion," he said. Even high-profile and luxury brands are getting into the act."

At the start of the year, legendary Italian fashion house Dolce & Gabbana launched their first line of hijabs and abayas - some extravagantly patterned - for Muslim customers in the Middle East.

Though Turkey is a constitutionally secular state, the conservative ruling Justice and Development Party (AKP), co-founded by President Recep Tayyip Erdoğan, has advocated removing restrictions on the Muslim headscarf since it came to power in 2002.

In 2013, Turkey lifted a long-standing ban on wearing the hijab in state institutions. Last month the government for the first time allowed policewomen to wear the headscarf under their official caps or berets.

In the conservative Fatih quarter of Istanbul, Islamic fashion stores line the streets, which are awash with billboards advertising modest styles.

'Versace of Islam?'

"I covered my head three years ago. I didn't want to dress up like my mother because in the past the clothes headscarf-wearing women could wear were limited," said 16-year-old shopper Şeyma. "Now I can easily find whatever I look for."

Tourists from the Middle East are also coming to shop in Istanbul.

"I find many things: casual dresses, trousers, t-shirts and many pieces," said Dalia, a young woman from Saudi Arabia. "I come without anything and buy from here."

Not all Turkish Muslims like the trend, and see fashion as a Western tool aimed at turning Muslim women into consumer-oriented spenders.

"Islam seeks to form a modest Muslim identity, encouraging need-oriented consumption," said Hülya Şekerci, an activist with the Free Thought and Education Rights Association, Özgür-Der.

"On the contrary, fashion is a vicious circle encouraging excessive consumption. That's why we are against fashion and fashion shows," she said.

Hakan Yıldız, professor of political science at Istanbul's Bosphorus University, said Islamic fashion stores were clearly proliferating in Turkey.

But "we need at least a generation to see how it will evolve," he said, adding that it would need "at least 20 years more to see if a Versace of Islam will emerge."