The theme of this year's Edinburgh international festival is art and conflict; the opening concert might have been bombastic or elegiac, but it could hardly have been outright celebratory. Instead the Royal Scottish National Orchestra and composer/conductor Oliver Knussen performed three of the most radical orchestral works composed in the years just before the first world war – works from Russia, France and Austria, each extravagantly colourful, intensely strange and eerily premonitory. They made for an intriguing prelude to the next three weeks.

The evening opened with Premonitions: the first of Schoenberg's glittering Five Pieces for Orchestra, played in rapt whispers and tight-sprung gestures. Knussen brought out the tender heart of the score with a gentle, lilting third movement (Colours), but he also honed in on the dank smudge that ends the work, that final chord so unnervingly inconclusive. There were darker shades of murk to come in Scriabin's Prometheus, Poem of Fire. Pianist Kirill Gerstein provided long, smouldering passages that sparked deftly and didn't let the flames ignite too soon; Knussen kept a long view, too, saving the real blaze for a thrilling outburst from the Festival Chorus at the end.

After the interval we heard Le Martyre de Saint Sebastien – Debussy's bizarre and sumptuous incidental music written for a theatrical mystery by the Italian poet and soldier Gabriele d'Annunzio. Here, I missed some flux and shimmer in Knussen's conducting: his insight was almost too forensic. But his composer's ear for colour and clarity illuminated beautiful moments in the score, and the RSNO showed off their flair for French music with some luminous textures. Claire Booth was a magnetic soloist, her voice forthright, sensual, lithe. The Festival Chorus did admirably, too; they couldn't quite muster the seductive sheen to make convincing sirens, but their final ringing chord was heroic.