It may look little more than blackboard scrawls to the untrained eye, but a Cy Twombly work fetched $70.53 million in New York, setting a new auction record for the painter.

A smattering of applause broke out in the room after bidding concluded for the star lot of Sotheby's main evening post-war and contemporary art auction of the fall season.

"Untitled" was produced by the US artist as part of his Blackboard series in 1968, using oil-based house paint, wax crayon and pencil on canvas.

The former army cryptographer painted six bands of repeated loopy lines on a gray background, which was sold by a prominent US collector to benefit a reform temple in Los Angeles.

Sotheby's said the price set a new record at auction for the artist, just edging out the previous record of $69.6 million.

Twombly was born in Virginia but based himself primarily in Italy from 1957 until his death in 2011 aged 83 in Rome.

Another standout of the night was an Andy Warhol acrylic silkscreen of Mao Zedong, from the artist's first series of the late Chinese communist leader, which sold for $47.51 million.

Sotheby's said it was the highest price paid for a Warhol of the week of auctions at its showroom and that of arch rival Christie's.

A Jackson Pollock, "Number 17, 1949," sold for $22.93 million, at the lowest end of its estimate, as did a Lucio Fontana "Concetto Spaziale, Attese" for $16.15 million.

Christie's evening sale of contemporary and post-war art on Tuesday netted $331.8 million in sales and set auction records for seven artists, including Fontana and French-American artist Louise Bourgeois.

At Christie's, Fontana's "Concetto Spaziale, La fine di Dio" -- a yellow egg slashed in the canvas -- sold for $29.17 million.