Police on Tuesday said a woman has been picked up by mainland authorities in connection with the murder in Hong Kong of socialite Abby Choi, bringing the total number of arrestees to seven.

The woman, 29, was handed over to Hong Kong officers at Shenzhen Bay Port.

She is suspected of having assisted one of the murder suspects.

Meanwhile, the mother of the murdered socialite is seeking a court order to block Choi's former father-in-law from selling a luxury property on Kadoorie Avenue.

Cheung Yin-fa filed a writ at the High Court against Kwong Kau, one of three people charged with Choi's murder.

Cheung wants the court to declare Choi as the beneficial owner of the flat, and that Kwong only holds the title deeds as a trustee.

The mother is also hoping to stop Kwong from selling, disposing, transferring or dealing with the flat without her prior consent or knowledge.