A multi-million pound painting by the late American artist Jean-Michel Basquiat has been the victim of vandalism in a mystery felt tip pen attack.

Cadillac Moon 1981 one of the best known works by the African American painter who started out as a graffiti artist in New York, was defaced despite being under heavy guard at Paris's Modern Art Museum (MAM).

Due to the abstract nature of the neo-expressionist Cadillac Moon 1981 it took the exhibition restorer's trained eye to spot the new 2cm-long felt scribbles.

It is believed the vandalism took place during the day so may well have been committed by a visitor to the exhibition. There has been speculation the felt tip attacker was a fan bent on keeping Basquiat's anti-establishment art "alive".

The painting has been on permanent exhibition at the gallery since October 15 but has now been taken down while a full criminal inquiry takes place.

Jean-Michel Basquiat was the first American graffiti artist of African descent to become an international art star, and was hailed a major artist of his genre after his death from a heroin overdose in 1988 at the age of 27. The neo-expressionist painter of Puerto Rican and Haitian origin began spraying buildings in Lower Manhattan in the late 70s under the pseudonym Samo before later collaborating with Andy Warhol, the pop artist, in the mid-1980s. Basquiat's paintings now fetch huge prices, with an untitled work from 1981 sold at Sotheby's New York in 2007 for $14.6 million (£9 million).

Image credit: Cadillac Moon 1981 by Michel Basquiat Acrylic and crayon on canvas, 162,5 x 172.7 cm