HONG KONG (DPA) - Two Saudi sisters who have been hiding in Hong Kong since September faced an uncertain future on Thursday (Feb 28) as they reached the last day of their permitted stay in the autonomous Chinese city.

"We're terrified that we'll be forced to return to Saudi Arabia," they said on Twitter under the handle HKSaudiSisters on Wednesday (Feb 27).

"We applied for an emergency rescue visa for a third country over two months ago. We (had) hoped that our emergency visa (would) be granted without delay."

The sisters, who say they have converted to Christianity, claim they fled from a family holiday in Sri Lanka to Hong Kong, where they hoped to board a connecting flight to Australia.

They claimed on Twitter that they were intercepted at Hong Kong airport by Saudi officials and have since gone into hiding.

The pair, who have identified as "Reem and Rawan", claim to have moved 13 times to avoid detection.

They said that Saudi Arabia cancelled their passports but they are afraid to go to the Hong Kong consulate to renew them.

Hong Kong is not a signatory of the 1951 Refugee Convention and would-be asylum seekers often languish for years as they wait to be sent to a third country.

Hong Kong's immigration department told dpa that it does not comment on individual cases.

Mr Michael Vidler, the Hong Kong lawyer representing the sisters, did not immediately respond to requests for comment.