U.S newsman Anderson Cooper underwent emergency surgery for appendicitis on Sunday night (30Nov14).

The anchorman took to Twitter.com to reveal he had an appendectomy, which explained his absence from his show, Anderson Cooper 360, on Monday (01Dec14).

Fans voiced their concern at Cooper's mystery disappearance when he was replaced by fellow newsreader John Berman.

On the microblogging site, the star insisted he would be back on air on Tuesday (02Dec14).

He writes on Monday, "I'll be back on air tomorrow. Had an appendicitis and had to have sudden surgery last night."