Missing five-year-old April Jones appeared to get into her abductor's van willingly, police have said, with nothing as yet to suggest there was a struggle.

The little girl was last seen by another child getting into the driver's side of a grey van which drove off in the Mid Wales town of Machynlleth at about 7pm on Monday.

Detective Superintendent Reg Bevan, from Dyfed Powys Police, told a media conference on Tuesday that he was not sure whether April had been led to the vehicle or went there herself. He said: "The indications are that she got into the vehicle willingly."

Asked if there were any signs that there was a struggle, he said: "It's very difficult to give an exact account of what happened. There's nothing to suggest at this stage that there was a struggle when she got into the car."

Investigators are now trying to get accurate information from the children who were with her around the time she was kidnapped. April got into a grey van that has been described as small at the front and large at the back.

Mr Bevan went on: "That could be interpreted as something small to a Ford Connect van, something like a Land Rover, and also that April got into the driver's side. That may well be that she got in with the driver, but of course that could mean that it's a left-hand-drive vehicle. The colour has not changed, that's as we initially gave it - grey."

Repeating pleas for any information, he said the force would be combing through CCTV to find out what happened and initially concentrating searches in the immediate area. He said specialist officers are supporting April's family during what must be "their worst nightmare".

Mr Bevan said: "The family, as you would imagine, it must be their worst nightmare. As you would expect, it is a very, very difficult time for them. But we do have specialist advisers with them and we will provide them with all the support that we can."

Police have an initial description of the suspect but have not yet released it. They have appealed for anybody with relevant CCTV footage to come forward.

Volunteers, who had been congregating at the local leisure centre, are now helping with a mass police-organised search for April. Each group, consisting of 20 people and led by an expert, has been given an assigned area to scour. Reports said the advice given to those taking part was not to pick up any piece of child's clothing they discovered, in case such an item may yield key forensic clues.