There are composers who conduct, and conductors who compose, but very few of them are equally good at both. The Hungarian Peter Eotvos is one of those rarities. Now 62, he first attracted attention as an expert conductor of the most complex contemporary scores, but increasingly his achievements as a composer have made their mark too.

Eotvos took on both roles with the London Sinfonietta, showing his wonderful precision as an interpreter in Messiaen's now classic Oiseaux Exotiques, with Paul Crossley as the solo pianist, and in the exemplary first performance of Paraphrase (Densités II), by the 33-year-old Portuguese composer Pedro Amaral. If Amaral's title has a Boulezian ring to it, then the first half of his piece, with its intricate, motoric ensemble writing strongly recalls the later music of the same composer. Then, after a pivotal piano solo, it seems to change direction, focussing instead on a single, steadily expanding trumpet melody; how the two sections depend on each other is hard to understand.

Then it was on to Eotvos the composer. His Snatches of a Conversation from 2001 is essentially a jazz-inflected work for solo trumpet, played wonderfully by Marco Blaauw using an instrument with a double bell that enables him to alternate between different kinds of mute at high speed, but there is also a part for a speaker (Omar Ebrahim) who delivers a fragmentary, often surreally nonsensical text, the "snatches" of the title. The connection between the two elements is obscure, but it coheres, in an attractive almost playful way.

There's an element of mystery also about Eotvos's "action piece" Triangel, in which a solo percussionist (the superb David Hockings) led the Sinfonietta through a series of confrontations in which various percussion instruments, are combined with different sections of the ensemble in turn. It's more a ritual than anything else, but one whose purpose remains elusive, though some of the sounds it conjures up are powerfully original.