Sotheby's contemporary art sale starts week 2 of London auctions

* House's fourth biggest auction of its kind in London

* Andy Warhol's "Mao" sells for 20 times previous price

* Last week was Sotheby's biggest ever sale series in London

By Julia Fioretti

LONDON, Feb 13 (Reuters) - Paintings by Andy Warhol, Cy Twombly and Gerhard Richter led the pack at Sotheby's evening sale of contemporary art in London, only a week after the auction house beat all records for a sale series in the British capital.

The contemporary art auction fetched 88 million pounds ($146 million) on Wednesday evening, at the top end of expectations, making it the fourth highest sale of that type for Sotheby's in London, it told Reuters by telephone on Thursday.

Buyers from 40 different countries took part in "frenzied bidding" for the 57 lots on offer, of which 10 failed to sell, Sotheby's said.

Gerhard Richter's "Wand (Wall)", painted in 1994, was the top lot, selling for 17 million pounds ($28 million) and beating its pre-sale estimate of 15 million pounds.

It had been shown in 20 museum exhibitions but had never before been offered for sale, Sotheby's said.

The New York-based auctioneer smashed records last week when its sales of impressionist, modern and surrealist art were the highest ever for any category in London, totalling 216 million pounds, it said last Friday.

Sales by rival auction houses Sotheby's and Christie's last week fired the starting gun for the February auction season in London, with buyers dishing out over 410 million pounds, according to calculations by Reuters.

HUNGER IN THE MARKETPLACE

The contemporary sale featured another piece never before seen on the market, the 1961 painting "Head (Other OTC: HEDYY - news) on a Green Sofa" by German-born British artist Lucian Freud, which fell just short of the top end of its pre-sale estimate, fetching 2.9 million pounds.

Andy Warhol's "Mao", (1973), part of the Mao series he painted just after U.S. President Richard Nixon's visit to China in 1972, was bagged for 7.6 million pounds, almost 20 times its price when it was last sold at auction in 2000, Sotheby's said.

"Untitled (Rome)", (1964), by U.S. artist Cy Twombly, exhibited in public for the first time, set a new record for the artist at 12 million pounds, well over its pre-sale estimate.

"What we saw last night was huge hunger in the marketplace (and) incredible energy in the salesroom," Alex Branczik, head of contemporary art in London at Sotheby's, told Reuters.

The London art market has been riding high recently, with super-rich buyers from emerging markets sending prices for pieces by the likes of Picasso and Camille Pissarro to record levels.

Sales for contemporary art typically trail those of impressionist, modern and surrealist art, Branczik added.

But emerging market buyers have been showing an increasing interest in contemporary art, with buyers from Latin America increasing their activity by 45 percent between 2012 and 2013, according to Sotheby's.

The contemporary art sales continue on Thursday with a daytime auction at Sotheby's and an evening one at Christie's.