Jill McGivering in Hong Kong: "The ruling has sparked a bitter political row"

The 18 mainland Chinese can now stay in Hong Kong until there is a full court hearing of their case.

The deportations were ordered under legislation passed when Britain returned Hong Kong to Chinese control.

The authorities say the mainlanders did not get permission to enter Hong Kong on a permanent basis and should return to China and undergo screening by Hong Kong immigration authorities.

The 18 say they are entitled to live in Hong Kong because their parents were born there and they want to be with their families.

Ruling came just hours before the deportation

Lawyers representing the mainlanders sought a judicial review hours before a deadline on Monday for them to leave.

The BBC Hong Kong correspondent Jill McGivering says the battle is far from over, but that it could clear the way for hundreds of other people in the same situation to stay in Hong Kong while they fight deportation.

Controversial abode ruling

The BBC's Jill Mc Givering in Hong Kong: "There are thought to be several hundred people in this situation"

The legal position of the 18 mainland Chinese has been complicated by a controversial ruling by Hong Kong's Court of Final Appeal last month.

It established that any mainlander with one parent permanently resident in Hong Kong has the right of adobe in the territory, even if he or she was illegitimate, or if the parent only became a permanent resident after the child was born.

It is estimated that 300,000 to one million people are affected.

But the Court of Final Appeal also upheld the Hong Kong government's rule that people wanting to claim abode must first apply to the Hong Kong authorities for a special entry certificate before they arrived, which this group had not done.

Lawyers representing the 18 mainlanders argued it was unreasonable to expect their clients to comply with a procedure which hasn't yet been implemented.

Hong Kong - Beijing tension

The Court of Final Appeal ruling has led to tension with Beijing.

China has told Hong Kong to correct the ruling, saying that a judgement allowing hundreds of thousands of mainland immigrants the right to live in Hong Kong violated the Basic Law - the territory's post-handover constitution.

Our correspondent says this has raised fears in Hong Kong that Beijing might overturn the ruling - a move which could undermine confidence in Hong Kong's legal autonomy.