The UN's refugee agency said on Tuesday it was investigating the case of Saudi teenager Rahaf Mohammed al-Qunun who fled from her family and barricaded herself inside a Bangkok airport hotel to prevent Thailand expelling her.

Al-Qunun accused her family of subjecting her to physical and psychological abuse after she boarded a plane in Kuwait and flew to Thailand last weekend.

Thai authorities finally permitted the 18-year-old to enter the country late on Monday, after she was held for nearly 48 hours at Bangkok's airport with authorities initially threatening to deport her. The country's immigration chief later reversed plans to expel al-Qunun citing concerns for her safety.

She is currently staying in Bangkok with her application for refugee status being processed by UNHCR before she can seek asylum in a third country.

"It could take several days to process the case and determine next steps," Giuseppe de Vincentiis, UNHCR's Thailand representative, said in a statement.

"We are very grateful that the Thai authorities did not send back [al-Qunun] against her will and are extending protection to her."

The Saudi teenager said she was certain she would be jailed if she were sent back to Saudi Arabia.

Saudi Arabia's embassy in Thailand denied reports that Riyadh requested the extradition of al-Qunun.

Thailand's immigration police chief, Surachate Hakparn, met on Tuesday with Saudi embassy officials and said they told him they're satisfied with how the case of the young woman has been handled.

"The Kingdom of Saudi Arabia has not asked for her extradition. The embassy considers this issue a family matter," it said in a post on Twitter.

Push for asylum

Meanwhile, legislators and activists in Australia and Britain urged their governments to grant al-Qunun asylum.

US-based Human Rights Watch (HRW) called on Australian officials to allow al-Qunun into the country.

HRW's Australian director Elaine Pearson said since Australia has expressed concern in the past about women's rights in Saudi Arabia, it should "come forward and offer protection for this young woman".

The Australian government said it was monitoring the case closely highlighting that "the claims made by Ms al-Qunun that she may be harmed if returned to Saudi Arabia are deeply concerning".

Senator Sarah Hanson-Young called on her government to issue al-Qunun an emergency travel document so she could fly to Australia to seek asylum.

Al-Qunun's case has drawn new global attention to the kingdom's strict laws, including the male guardianship system.

It also comes at a time when Riyadh is facing mounting pressure over the killing of Saudi journalist Jamal Khashoggi at its consulate in Istanbul in October, and over the humanitarian consequences of its devastating war in Yemen.