LONDON - British retailers reported a stronger-than-expected sales rise in October after a September slowdown but global supply chain problems reduced their stocks to the lowest level since records began in 1985, the Confederation of British Industry said.

The CBI's monthly distributive trade survey showed the headline sales balance for retailers picked up to +30 in October from +11 in September which was its lowest level since March, when many retailers were closed during a COVID-19 lockdown.

Economists polled by Reuters poll had mostly expected a reading of +13.

Sales were expected to pick up a bit more in November although retailers were keeping an eye on the latest rise in coronavirus cases in Britain.

But the survey's measure of stock adequacy sank to -23 in October, the seventh month in a row that it hit an all-time low. The shortages were expected to ease only moderately in November.

"Disruption to supply chains, combined with staff shortages and uncertain public health conditions mean retailers are finding it difficult to plan for the winter ahead," CBI economist Ben Jones said.

Finance minister Rishi Sunak should help the sector by reforming the business rates tax system when he announces a half-yearly budget plan on Wednesday, Jones said.

The CBI has long argued that the system is out of date and penalises companies which invest in energy efficiency.

(Reporting by William Schomberg, editing by Andy Bruce)