WASHINGTON (AFP) - A White House national security official has been dismissed after being identified as the source of tweets insulting the administration that were sent under a fake name, news reports said on Tuesday.

A White House source said this official no longer works for the administration of President Barack Obama, but declined to give details.

The Daily Beast news website reported that Mr Jofi Joseph, 40, who worked on nuclear non-proliferation in the National Security Council, was let go after being identified as the author of messages sent under the name "@NatSecWonk".

Tweets sent under this account assailed both the Obama administration and Republicans, as well as conservative political commentators, The Daily Beast said.

The comments targeted a close friend and adviser of the president, Ms Valerie Jarrett, foreign policy speech writer Ben Rhodes and even Secretary of State John Kerry.

Another news website, Politico, said it had received an email statement from Mr Joseph.

"It has been a privilege to serve in this administration and I deeply regret violating the trust and confidence placed in me," Mr Joseph was quoted as saying in the email.

"What started out as an intended parody account of DC culture developed over time into a series of inappropriate and mean-spirited comments. I bear complete responsibility for this affair and I sincerely apologize to everyone I insulted," he wrote, according to Politico.

The White House issued no official statement.

The Twitter account "@NatSecWonk" was no longer active as of late Tuesday.