Fashion chain H&M said it is launching a one-off collection called Harmony that will hit stores in September.

The collection will be sold in all H&M markets, a spokesperson told just-style, with about 120 of its bigger stores stocking the full range and other stores selling a limited range within its ladies'clothing and young fashion divisions.

Harmony, which will be sold for the duration of the autumn season, is part of a pledge to keep up with the newest trends and to "surprise people", the spokesperson said.

The collection's hallmarks are soft and easy, feminine body-skimming shapes which H&M said "transcend the conventional boundaries between evening clothes, homewear and athletic wear".

"By mixing leggings, wrap tops, cashmere jumpers and knitted accessories with tailored pieces and denim, Harmony reminds us that fashion rules are meant to be broken and that being comfortable is the key to personal style," said H&M's head of design, Margareta van den Bosch, in a press release.

H&M said it took inspiration for the collection's style from ballet, Pilates and yoga. Pieces will be priced from EUR7.90 (US$9.93) for accessories to EUR39.90 for knitwear.

The spokesperson told just-style the company never commented on predicted financial expectations for individual collections but said further limited-edition collections were likely.

H&M has seen previous one-off ranges including those by designers Stella McCartney and Karl Lagerfeld fly off the shelves.