Batsheva Dance Company, Sadler's Wells/Riverside Studios, London

On Tuesday night at Sadler's Wells, secret service officers were seen checking under the seats. The next night outside Riverside Studios, protesters tried to persuade punters to boycott the show. What contemporary dance company could possibly merit such attention? An Israeli one, apparently. Batsheva is hardly a political entity, but it's funded by Israel's government, its performers include none of Arab extraction, and it is "proud to be considered Israel's leading ambassador".

Whatever your position on the above, at first sight the artlessly dressed Hebrew youth that filled the Sadler's Wells stage seemed easily dismissable. Barefoot in cut-offs and T-shirts as if they'd just bowled in off the beach at Haifa, they look too chunky and low-slung to be dancers. The women have bosoms and bums, for goodness sake, and the guys look cut out more for frisbee than frappés.

Yet within seconds they have your attention, standing and staring, full face, for longer than is comfortable, before silently leaving the stage. Ohad Naharin, the director whose work has shaped Batsheva's identity for 18 years, is strong on such framing devices. The short works that make up Three, which runs without interval for just over an hour, are separated by a dour-faced man carrying a TV screen on which his own face (smiling) announces what is about to happen. Offering pointers such as that the music (barely-there Brian Eno) "is very very quiet", and "there will be blackouts" – as if we wouldn't notice – it's clear that this is Naharin's private jab at persistent requests for programme notes.

Some of Bach's Goldberg Variations accompany the first section, using the sublime recording by Glenn Gould with its alto of tuneless humming. Intuitively, beautifully, Naharin picks up on the piano's meanders, translating music into vivid sensation as the dancers weave and flex, their jutting, hunkered movement erupting into suddenly elegant point-footed exclamation marks. And as the bassline of the piano pursues its plodding crotchets, Naharin overlays it with a quaver pulse of padding footfalls. Masterly.

Nine women take charge of the middle section, which sees Naharin's minimalism reduced to simple floor exercises. Yet even the most prosaic of these – arms held stiff like the hands of a clock, bottoms swishing the floor like parquet-polishers – become special given such technical rigour.

But is anything ever truly apolitical? Perhaps we were primed to look for it, but there it is in Three: the quad-bashing marching, the arms-up surrender, the wriggling on the stomach with imaginary rifle (or was the imaginary rifle mine?). Then there are the bursts of youthful defiance. Two men in a passionate, only-half-joking ballroom clinch. Mid-air mooning, as dancers of both sexes jump with their backs turned and, for a split-second, gleefully bare their buttocks.

Mamootot, an in-the-rounder on subsequent nights in Hammersmith, was harder to like. The conjuction of perversely ugly costumes with radical nudity, extreme physical discipline with let-it-all-hang-out splurges, and severely undramatic longueurs, made me burrow my head in my notes when the dancers walked round shaking hands with spectators and staring long and hard into their eyes. Call me chicken, but I don't want to get that close.