Lil Wayne, left, M.I.A. and Jay Z perform Swagga Like Us. M.I.A. was due to give birth on Sunday, when she appeared on the show. (Mark J. Terrill/Associated Press)

British rapper M.I.A. says she gave birth to a son after going into labour just hours after she gave an electrifying performance at the Grammys last Sunday.

M.I.A., real name Mathangi Arulpragasam, announced on her MySpace blog on Saturday that her baby — born Feb. 11 — is "healthy, fine, beautiful, and the most amazing thing on this planet."

"Me and baby are putting our tour dates for 2010 together, making mix tapes, and figuring out a way to break out of the hospital!" she wrote.

She was at the Grammy show in Los Angeles strutting onstage while performing Swagga Like Us, based on a sample of her hit Paper Planes, with Kanye West, Jay-Z, T.I. and Lil Wayne. The 31-year-old singer was due that day.

M.I.A. had two Grammy nominations: her track Paper Planes was nominated for record of the year, while Swagga Like Us was in the running for best rap song.

Her track O Saya, featured in the film Slumdog Millionaire, is shortlisted for best original song at the Oscars.

The father of the baby is her fiancé, musician Benjamin Bronfman, a member of Canada's eminent business family.

A representative says the couple has declined to release the baby's name.