A British man was due in court on Thursday after being extradited from Germany for allegedly launching cyber attacks against two of Britain's best known high-street banks and attempting to blackmail them.

Services at Lloyds and Barclays banks were disrupted by the cyber attacks in January, the National Crime Agency said in a statement following a joint investigation with Germany's federal crime bureau BKA.

The attack on Lloyds Banking Group lasted three days and prevented some customers using their online accounts, although a bank spokeswoman said that no customer details or accounts were compromised.

Daniel Kaye, 29, allegedly orchestrated so-called distributed denial of service (DDoS) attacks.

He also faces a charge that he "endangered human welfare" with an alleged cyber attack against Lonestar MTN, Liberia's biggest internet provider, the NCA said in its statement on Wednesday.

He was extradited on Wednesday on a European arrest warrant.

"The investigation leading to these charges was complex and crossed borders," said Luke Wyllie, senior operations manager at the NCA. 

"Cyber crime is not victimless and we are determined to bring suspects before the courts," he said.