British counter-terror police have arrested two more people in relation to the London subway attack that left 30 people injured, bringing the total number of arrests to five.

Key points: Police say investigation is 'fast-moving', arresting a total of five men since attack

Police say investigation is 'fast-moving', arresting a total of five men since attack Three men aged 25, 48, 30 were arrested in Newport, Wales, while two men aged 18 and 32 were arrested in Dover and Stanwell

Three men aged 25, 48, 30 were arrested in Newport, Wales, while two men aged 18 and 32 were arrested in Dover and Stanwell The five men remain custody but have not been charged

A 25-year-old man was arrested on Tuesday evening in Newport, Wales, while two others, aged 48 and 30, were detained at another address in the Welsh town in the early hours of Wednesday, London police said.

"This continues to be a fast-moving investigation. A significant amount of activity has taken place since the attack on Friday," said Commander Dean Haydon, head of London police's Counter Terrorism Command.

"We now have five men in custody and searches are continuing at four addresses. Detectives are carrying out extensive inquiries to determine the full facts behind the attack."

Two other men arrested over the weekend — an 18-year-old refugee from Iraq and a 21-year-old from Syria — remain in custody. Neither has been charged.

Investigators were on Sunday searching the 21-year-old's home in Stanwell, about 25 kilometres south-west of central London, heading toward Heathrow Airport.

Police had earlier arrested the 18-year-old man in the city of Dover — the port linking England to France — and raided a property in Sunbury, which neighbours Stanwell.

Police earlier raided a property in Sunbury, which neighbours Stanwell. ( AP: Victoria Jones/PA )

Both were said by local media to have links to a property in Sunbury-on-Thames, a town just outside London, where police were carrying out a major search.

The house belongs to a couple who have fostered hundreds of children, including refugees. The leader of the local authority was quoted as saying the 18-year-old was an Iraqi who had come to Britain as an orphan.

The attack at the Parsons Green underground station left 30 people injured when a homemade bomb, placed inside a bucket that was enclosed by a shopping bag, partially detonated inside a subway car during peak hour last week.

Experts said the bomb could have been far more destructive if it had fully detonated.

Sorry, this video has expired A white container inside a plastic bag burns on the London Underground train. (Photo: Twitter/Rigs)

In the aftermath, the authorities raised Britain's threat level to its highest rank of critical, meaning an attack was considered imminent, but lowered this after arresting two men on Saturday.

Islamic State militants said they were responsible for the attack although both British and US officials have cast doubt on the claim, saying there was no evidence any recognised militant group had ordered or organised the bombing.

Two days after the attack, all but one of the people injured had been released from hospital, Britain's National Health Service said.

One person was still being treated at Chelsea and Westminster Hospital, which has a special unit for treating burns.

This bombing was the fifth major attack regarded by authorities as a terrorist incident in Britain this year which have claimed the lives of 36 people.

The Parsons Green station reopened on Saturday. ( Reuters: Peter Nicholls )

AP/Reuters









