Berlin is locked in art fever, with four powerful exhibitions going ahead including work by Jeff Koons and Paul Klee.

At the Mies van der Rohe-designed New National Gallery, US contemporary artist Koons is parading a glittering array of huge sculptures and paintings.

On a lower floor is a superb selection of work by the late German expressionist painter Klee, garnered from both private and international collections.

Simultaneously, the 13th Art Forum - Berlin's International Fair for Contemporary Art - is being staged at the city's Funkturm trade fair grounds.

This brings together 127 galleries from 26 countries, and around 2,000 participating artists from across Europe, as well as from Russia, India, South Africa, the USA and Central America.

Mumbai-based artist Riyas Komu, seen as one of the most promising contemporary Indian artists, is meanwhile giving his first German solo exhibition of sculptures and paintings at the Bodhi Gallery.

One of 37-year-old Komu's epic sculptural installations titled "Watching the other world spirits from the gardens of Babylon" is seen as a take on the US invasion of Iraq with its immediate physical and traumatic impact on the individual and his or her surroundings.

Wagon-like constructions, carved from used wood and detailed with skull and brain depictions refer, he says, "to the origin of all militaristic methods of destruction, namely mankind."

Komu is often termed a champion of the underdog - with his sculptures and paintings questioning what people hide behind the masks of their faces. He employs a dozen workers in Mumbai who all come from the village where he used to live.

"It is interesting to introduce traditional craft into my work. Such craft used to be used only for decorative or luxurious purposes, whereas I use it in an entirely different context," he said.

The director of the 2008 Berlin Art Forum is Sabrina van der Ley, who shortly will become curator of contemporary art at the Kunsthalle (Art Hall) in Hamburg.

"Since the Art Forum began in Berlin in 1996 it's grown into the biggest art fair in Germany, which was what everybody was hoping for," she told Deutsche Presse-Agentur dpa.

"In those 13 years it has also become the most important art market place in Germany, especially for contemporary art," she says.

This year's Art Forum sees more than half the exhibitors coming from abroad. But Berlin is well represented with 28 galleries, say the organisers, who promise "exciting new encounters" with exhibitors from Spain, Austria, Russia, India and, for the first time, South Africa.

The Nordic Countries are again in force, as are the Benelux countries with a stepped up representation. Thirty-one galleries are first time participants in Berlin.

Three years ago Mihai Pop and Adrian Ghenie founded the artist-run gallery "Plan B" aimed at an international audience in Cluj, the largest city in the Romanian province of Transylvania.

Now after organising last year's Romanian Pavilion at the Venice Biennale, they are in Berlin to show the work of six artists operating in different media. Among them is David Nuur, who attracts attention with subtle thought sculptures.

Twice daily, international experts will be shedding light at Art Forum talks on the increasingly global art world.

Mexico's Nino Monocal presents a solo exhibition of paintings by the multi-facetted and emerging artist Duvier del Dago in Berlin, and Berlin-Beijing gallerist Alexander Ochs displays sculptures and paintings by outstanding Chinese artists.

Yin Xiuzhen's "Bras" (20,000 euros) and Yang Shaobin's "My Left Leg" (230,000 euros), earlier displayed at the Shanghai Art Biennale, are to be seen at the Art Forum.

The Korean painter Sun Young Byun's "The House in the Painting, The Painting in the House" is also shown alongside the star Chinese artist works. The Art Forum runs until November 3.