Detectives have been granted a further 36 hours to hold one of three men on suspicion of kidnap and rape of a three-year-old taken from her home.
The men are being held in Cardiff after the girl was allegedly abducted from the Rumney area of the city on Monday.
A 26-year-old was arrested after a police chase in Wiltshire early on Tuesday. Two others, aged 34 and 47, had already been arrested in Wales.
Officers are continuing a forensic examination of a property in Newport.
Gwent Probation Service has confirmed that the property was used to house newly-released prisoners.
Northumbria Police investigating the abduction of a six-year-old girl in Tyneside have confirmed they are liaising with detectives in south Wales.
For over a week they have been trying to trace a man who snatched the girl from the bath of her home and left her screaming and naked in an alley. She had been sexually assaulted.
South Wales Police were granted more time to hold a 47-year-old suspect on Thursday morning. They had already been given an extra 36 hours to question the two other men.
They believe the three-year-old was raped after being taken from her home between 1900 and 2300 GMT on Monday.
A member of the toddler's family told BBC Wales she is doing okay under the circumstances and that she did not really understand what had happened.
The relative added that the child - who has not wanted to return home to Rumney - was "very quiet and hasn't said very much at all".
A 34-year-old man was arrested first at 0023 on Tuesday.
Police were then looking for a certain car when colleagues in Wiltshire spotted the L-registered grey Ford Escort going through a red traffic lights without headlights on near Marlborough.
They pursued the car along the M4 for about four miles where it left at junction 15 before heading for 10 miles down the A4 towards Hungerford where it crashed.
The driver of the car was arrested at the scene at 0340 GMT. By that stage a third man, aged 47, had already been arrested in Cardiff.
The child was airlifted to hospital from the scene. Although she was not badly hurt in the collision, she is said to have sustained other significant injuries.
House-to-house inquiries are ongoing in Rumney
Police are continuing house-to-house inquiries in Rumney and said they were pursuing "a number of lines of inquiry".
Superintendent Josh Jones, Deputy Divisional Commander for Cardiff, said: "This is an extremely rare event which makes it all the more shocking.
"Rumney is a close-knit community and we ask the residents to work closely with us in providing any information that they can. We will continue to provide a very visible police presence in the area."
Speaking outside Cardiff Central Police Station on Wednesday, Detective Superintendent Paul Kemp said: "The allegations are horrendous and I would urge anyone who has further information to contact us."
The incident room can be reached on 02920 222111 or Crimestoppers anonymously on 0800 555111.