HUNDREDS of volunteers are expected to join the hunt for missing 22-year-old Sian O’Callaghan again today after a second police appeal to help comb Savernake Forest for clues.

The plea comes following an overwhelming response to yesterday’s search through the vast wooded area near Marlborough.

As people combed the woods, an anonymous donor put forward a £20,000 reward for information that leads directly to Sian being found.

Today’s volunteers are asked to meet at Postern Hill, in Savernake Forest, from 10.30am, sign in with police and receive a briefing first.

Yesterday more than 300 people, mostly from Swindon, were at the same site to help officers with the painstaking search of the last-known location of her mobile phone.

Sian has been missing since leaving popular nightclub Suju at around 2.50am on Saturday. She was thought to be walking to the home she shared with her boyfriend Kevin Reape in Westmorland Road in Swindon’s town centre.

Mr Reape and Sian’s family made a tearful plea for her safe return at a police press conference on Monday.

More than 60 dedicated officers are conducting enquiries into her disappearance.

Teams of specialist officers, police dogs and 34 volunteers of Wiltshire Search and Rescue (Wilsar) will again join members of the public today to search the 4,500-acre woodland.

Following yesterday’s turnout, Sergeant Warren Knight, police search manager, said he welcomed the help.

“It is such a vast area – at the moment it is the entirety of Savernake Forest – so the more we can eliminate from our enquiry the better,” he said.

“We had groups of around 10 people to one police officer so it was in manageable chunks. I have not seen this level of response before – it is definitely a help. The public’s help is always really valuable.

“The priority is to find Sian but if we can find any other evidence that could help locate her then we will be looking for that as well.”

Among the helpers was Mikey Jack, 19, of Stratton who plays football with Sian’s boyfriend.

He said: “I just want to help. I’ve been to Suju myself a few times and it’s not something you think would happen.”

Another group of friends who made the 15-mile journey included Rachel Ewart, 26, Maz Wakefield, 27, Terri Blackler, 26, and Mat Coles who shared some pals with Sian.

Mr Coles, 27, of the town centre, said: “She’s been to a lot of events and has a lot of friends but we never crossed paths properly. I was working in the Bell Hotel on Friday night but did not see anything. We just want to do what we can.”

Garry de la Pomerai, of international charity Search and Rescue Assistance in Disaster (SARAID), was one of a 10-strong team called in to help.

He said: “We have assisted Wiltshire Police before and are specialists in search techniques. We work with the UN and have been in Pakistan, Haiti and other places for major disasters.

“This was potentially the scene of a crime so you cannot just wander because you might destroy evidence. But this has been an excellent response from the public.”

A Salvation Army emergency response unit was also on hand to provide tea, coffee and food for volunteers.

Captain Gerald Nicoll said: “We were asked by the police to attend because there are so many people and we are here to provide refreshment for them.”

Yesterday Det Supt Steve Fulcher said his officers were working tirelessly and also restated his appeal.

He said: “Firstly, I’d like to thank the public and media for their ongoing support with our investigation. My teams are working tirelessly to find Sian and the community have been very helpful and understanding.

“We know that Sian had a LG E900 Optimus mobile phone with her on the night of her disappearance and I’d like to hear from anyone who finds a phone of this description.

“Sian left Suju and walked along the High Street in Old Town and there were a number of vehicles moving through the High Street between 2.55am and 3am. We would like to identify the people in those vehicles as possible witnesses.

“I’d also like to hear from anyone who saw any vehicles in or near beauty spots between Swindon and Savernake between 3am and 4am.

“I’d also like to take this opportunity to remind people to think about their personal safety and take basic measures such as always making sure someone knows where you are going and what time you will be home, stay with friends and try not to walk alone.”

Sian is described as white, 5ft 3ins tall, of medium build with brown asymmetric hair and green eyes. When last seen she was wearing a grey dress, black bolero style jacket, dark coloured tights and flat boots. She was carrying a dark handbag which had a beige flower attached.

Anyone with information is asked to contact Wiltshire Police on 0845 408 7000 or Crimestoppers 0800 555 111.