The battle for supremacy between the two next-generation DVD formats swung sharply in Blu-ray’s favour on Monday when Blockbuster, the leading US video rental chain, increased the number of stores stocking the discs.

Blockbuster said it would offer Blu-ray, a Sony-backed format, in 1,700 stores, compared with about 250 for HD-DVD, the rival format backed by Toshiba and Microsoft. Demand for Blu-ray was “significantly outpacing” rentals of HD-DVDs, it added.