LONDON, Nov 22 (Reuters) -

Hundreds of workers at British security company G4S have voted to strike for 48 hours in early December in a dispute over pay, trade union GMB said on Tuesday, warning the walk out could cause cash shortages over the Christmas period.

The G4S Cash workers deliver cash and coins to banks including Barclays, HSBC and Santander as well as supermarkets Tesco, Asda and Aldi, the union said in a statement.

A spokesperson for G4S, which was bought by American group Allied Universal last year, said the company was continuing to engage with its employees and the union.

"(We) hope to reach an amicable agreement without the need for industrial action," the spokesperson said.

The union said 97% of its G4S Cash members who took part in a ballot had backed industrial action, which is set to begin at 0300 GMT on Dec. 4 and last for 48 hours initially.

Their discontent forms part of a wider industrial unrest in the country this year, as pay rises fail to keep pace with soaring inflation.

"G4S Cash staff provide an absolutely vital service," GMB National Officer Eamon O'Hearn said.

"All they are asking for is a wage they can live on, that they can feed their families on, that they can treat their children this Christmas on." (Reporting by Muvija M, Editing by Kylie MacLellan)