Senior Democrats have warned President Donald Trump not to use a controversial memo as a "pretext" to fire the special counsel investigating alleged Russian involvement in the US election.

They warned that such action could trigger a constitutional crisis not seen since the Nixon era.

The memo, written by Republicans, accuses the FBI of abusing its powers.

President Trump approved the declassification of the memo and said it revealed a disgraceful story.

It accuses the FBI and the justice department of using an unsubstantiated and Democratic-funded report to obtain the warrant that gave permission to spy on an aide to Mr Trump.

Democrats said the release of the memo was aimed at disrupting investigations into alleged links between the Trump campaign and the Kremlin. President Trump has consistently denied any such collusion.

The FBI had warned against the memo's release and said key facts had been omitted.

(Source: BBC)