Britain's government said Tuesday it had launched an internal investigation into whether senior civil servants told a newspaper that opposition Labour leader Jeremy Corbyn was "too frail" to be prime minister.

Britain's Labour Party leader Jeremy Corbyn gestures after voting at a local polling station in his constituency in London, Britain, May 23, 2019. (Photo: VCG)

"The Cabinet Office (ministry) is investigating this potential breach of the civil service code fully and fairly just as it would any other," said a spokesman for Conservative Prime Minister Theresa May.

"If we are able to identify an individual responsible we will take disciplinary action."

Corbyn has called for an independent investigation, saying the story that appeared in The Times on Saturday had "undermined confidence in the principle of civil service neutrality".

The report quoted unnamed civil servants, who are supposed to be apolitical, as saying the 70-year-old leftist leader is "too frail and is losing his memory".

May's office said the government was "taking the matter extremely seriously".

The spokesman said the civil service took responsibility for enforcing its own code of conduct and "this is no different".