Princess Mary delights school girls during a visit to a playground in Saudi Arabia... as mothers clad in burkas snap selfies on their smartphones

Crown Princess Mary has taken time out of her five-day tour of Saudi Arabia to play with the country's school children.

The Australian-born royal was seen smiling as she visited a playground, reaching out a hand to help a young girl as she stepped off a slide.

Mary appeared delighted to spend time with the young girls who were dressed in their red-and-white school uniforms as she toured the country with her husband, Prince Frederik of Denmark.

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Fun and games: Princess Mary visited a playground where she interacted with a group of school girls

A royal meeting: The students appeared delighted to meet the Princess and gathered around her as an onlooker took photos

Talking business: The mother-of-four sipped tea while she participated in business delegations

The mother-of-four arrived in Saudi Arabia on Sunday where she and Frederik have planned a series of business meetings to discuss the issues of health, sustainability and design and with the goal of strengthening trade.

But talking business appeared far from Mary's mind as she engaged with the children, who appeared delighted to spend time with the Princess.

Mary dressed in a grey tweed coat for the occasion, which she paired with an all-black ensemble and black stilettos.

Royal duty: Mary dressed in a black-and-white full-length ensemble as she met with people on her five-day tour

The young girls were dressed in a white-and-white checked school dress which they wore over a long-sleeved white shirt, their hair tied up in pink ribbons.

They laughed as they slid down the slide and smiled as they gathered around Mary. 

While the playground visit was light-heated, Mary's tour of Saudi Arabia has not been without controversy.

Camera ready: Mary smiled as Frederik posed for a selfie while on a business tour of Saudi Arabia

The tour was almost cancelled earlier this year after human rights groups, including Amnesty International, voiced concerns about the country's human rights record - many suggesting the royal's visit would mean they accepted the political differences.

So far their trip has seen Mary participate in business delegations and take part in tours of the country.

On the same day she visited the playground, May and Frederik donned hard hats and hi-vis vests for a tour.

In one photo Mary is seen lovingly adjusting Frederik's hard hat, smiles on their faces. 

Royal meeting: The five-day trip began with Frederik and Mary meeting with the Saudi royal family

No headscarf: The Princess decided to forego a headscarf, which are not required for foreigners

Conservative: The 44-year-old Princess has remained covered up during the tour, dressing in a long black top, loose-fitting black trousers, a soft pink silk scarf and Dolce & Gabbana sunglasses

Earlier in their trip, Mary and Frederik were seen together with the Saudi royal family and met with King Salman bin Abdulaziz at the Royal Palace.

The 44-year-old Princess covered up for the occasion in a long black top, loose-fitting black trousers, a soft pink silk scarf and large Dolce & Gabbana sunglasses and was accompanied by 44 Danish representatives.  

The Princess decided to forego a headscarf, but while Saudi females are required to wear a headscarf and loose robes in public, scarves are not required for foreigners and some women choose not to wear them. 

Mary was later pictured shaking hands with various representatives dressed in a stunning, conservative black Prada coat, a pastel pink scarf and black trousers with her hair pulled back in a slick bun.  

Business trip: Pictures show Mary and Frederik with the Saudi royal family and meeting King Salman bin Abdulaziz at the Royal Palace

Focused: Princess Mary was looking stony-faced as she sat by her husband 

Optional: In 2013, Duchess of Cornwall Camilla opted for a simple blue headscarf while visiting Saudi Arabia (left) and in 2012, Kate Middleton wore a white scarf in Malaysia

In January 2015, First Lady of the United States, Michelle Obama, was criticised by both people in America and Saudi Arabia after she visited the country and decided not to wear a headscarf. 

American politician Hillary Clinton also decided to forego a scarf during her visit in 2012 and in 2013, Duchess of Cornwall Camilla opted for a simple blue headscarf while visiting Saudi Arabia - but did not cover up her hair.

Clinton did choose to don a headscarf during her visit to the historical Badshahi Masjid in Lahore in 2009 and Duchess of Cambridge Kate Middleton covered up with a white scarf at The Assyakirin Mosque in Malaysia in 2012.

Some suggest those who choose not to wear a headscarf are making a bold statement, while others believe it is impolite. 

Controversy: In January 2015, First Lady of the United States, Michelle Obama, was criticised by both people in America and Saudi Arabia after she visited the country and opted not to wear a headscarf

To wear or not? American politician Hillary Clinton decided to forego a scarf during her visit to Saudi Arabia in 2012 (left) but did choose to don a headscarf during her visit to Badshahi Masjid in Lahore in 2009 (right)

Modern Prince: Prince Frederik appeared relaxed as the group strolled through the palace grounds, wearing a tailored navy blazer, blue striped shirt and cream trousers

Prince Frederik appeared relaxed as the group strolled through the palace grounds, wearing a tailored navy blazer, blue striped shirt and cream trousers.

He completed his outfit with a pair of gold sunglasses and simple, black leather shoes.

The royal couple flew to the country to participate in a business campaign in the capital, Riyadh, and will head to Qatar's capital, Doha, on Wednesday where they will remain for two days.