Two suspected hackers have been arrested in London by detectives investigating a crippling cyber attack which brought down Washington DC's CCTV cameras eight days before the inauguration of President Donald Trump.

The Sun reported that police swooped on a house in Streatham, south London last month after the US government reported 123 of 187 security cameras in Washington went offline, amid fears it may be linked to an attempt on Trump's life.

Just hours before the 45th President was sworn in, a 50-year-old British man and a Swedish woman, also 50, were detained by the National Crime Agency.

Donald Trump waves to the crowds after being sworn in as President. The cyber attack brought down many of the CCTV cameras in Washington a week before his inauguration

It was believed the cyber attack could have been a dry run for another attempt on January 20, the day of the inauguration.

But Brian Ebert, a Secret Service official, told the Washington Post the safety of the Trump family and the general public had never been in jeopardy.

The security bill for President Trump's inauguration was at least £75million, with 25,000 armed police and National Guardsmen turning the city into a fortress.

But the Secret Service were concerned about the CCTV blackout, with cameras out of action between 12 and 15 January.

Archana Vemulapalli, Washington's Chief Technology Officer denied the city had paid a ransom to the hackers to get the cameras back online. He said they had removed the sophisticated software used by the hackers and rebooted the system.

The NCA said the man and the woman were arrested on January 19 and bailed until April 2017.