Detectives investigating the death of Sian O'Callaghan are still working to establish the identity of a set of human remains found at a second site.

Wiltshire Police have been scouring the national DNA database but have warned if no matches are found it could take "some time" to identify the woman.

Excavation work had been taking place at the site at Baxter's Farm in Eastleach, on the boundary of Oxfordshire and Gloucestershire, about 17 miles from Uffington, where Sian O'Callaghan's body was discovered.

Meanwhile, police search teams have been combing an area of countryside around four miles from the place where Miss O'Callaghan's body was found.

Flowers have been laid by the officers involved in the case next to a wooden cross, with the message: "To an unknown lady, now you can rest in peace."

A police spokesman said: "We can confirm that work to recover a second body at Eastleach has been completed and the scene released.

"Forensic investigations to establish the identity of this young woman are ongoing using DNA and the speed of this identification process relies on whether or not we have her DNA on a database.

"If we don't get a DNA match further investigations will need to be carried out which may take some time. The public can be assured that we will of course inform the victim's family wherever possible before releasing any details in the media."

Speculation has pointed to a young Vietnamese immigrant, Hai Nguyen, 20, who went missing from her temporary home in Swindon in June 2005. Local people assumed she had moved to London to seek work after arriving in the country in 2003.

Police are refusing to reveal who they believe the body parts belong to but say they could belong to a woman aged between 23 and 30, who would have been abducted in Swindon between 2003 and 2005. The force has no outstanding reports of missing women from that period.

A Wiltshire Police spokeswoman said searches at Claypit Lane, near Uffington, were for items belonging to Miss O'Callaghan that may have been discarded. Detectives have still not found Miss O'Callaghan's bag, boots, keys or phone.