LONDON - Britain will automatically enrol nearly 90,000 companies in a customs system in order to reduce the risk of Brexit disruption, the government said, its latest attempt to show it can leave the European Union without a deal if necessary.

More than 88,000 companies which are in Britain's value-added tax register will be allocated an Economic Operator Registration and Identification (EORI) number in the next two weeks, the finance ministry said on Wednesday.

So far, around 72,000 firms have registered for EORI numbers which identify them for customs authorities.

"As the government accelerates its preparation to leave the EU on Oct. 31, it's right businesses are prepared too," finance minister Sajid Javid said.

"This will help ease the flow of goods at border points and support businesses to trade and grow."

A group representing small businesses welcomed the move but said companies also urgently needed tax measures to boost cash-flow and adapt to any new trading circumstances from Nov. 1. "If the nightmare of a chaotic no-deal Brexit on Oct. 31 becomes a reality, our small traders will be the first ones off the cliff," Mike Cherry, chairman of the Federation of Small Businesses, said.

The FSB and the Confederation of British Industry, another employers group, have previously urged the government to issue EURI numbers automatically to businesses.

New Prime Minister Boris Johnson has said he wants Britain to leave the EU with a transition deal but he says he is prepared for a no-deal Brexit if the bloc does not renegotiate the deal it struck with his predecessor Theresa May.

Bank of England Governor Mark Carney has warned that many companies are not ready for the shock of a no-deal Brexit, adding to the risk of a shock for the economy.

Johnson's government plans to double the support available for customs agents to train new staff or invest in technology to help businesses complete customs declarations.

(Writing by William Schomberg) ((william.schomberg@thomsonreuters.com; +44 207 542 7778; Reuters Messaging: william.schomberg.reuters.com@reuters.net))