A day after suspending him from the primary membership of the party, the Congress on Wednesday night served a show cause notice to former external affairs minister K Natwar Singh.

"The show cause notice, including the suspension order, was sent to Singh late Wednesday night," highly placed Congress sources said.

The Congress Disciplinary Action Committee in a meeting late Tuesday night suspended Natwar from the party and decided to send a show cause notice to him asking why he should not be expelled from the party for misusing his position for procuring oil contacts from Iraq in 2001 under the Saddam Hussain regime.