The service said more than 340 calls were waiting to be answered at the time the critical incident was declared on Monday evening.

Liam Delap’s barnstorming display helped Ipswich register a first Premier League home win in 22 years with a memorable 2-0 victory over Chelsea to further damage their faint title prospects.

Chinese hackers remotely accessed several US Treasury Department workstations and unclassified documents after compromising a third-party software service provider, the agency has said.