LONDON (Reuters) - Mother and baby products firm Mothercare (>> Mothercare plc) warned on Wednesday that full year profit would miss analysts' expectations, making it the latest high street retailer to be hit by record Christmas discounting in Britain.

Mothercare, which makes about 70 percent of its revenue in Britain, said that group sales fell 6.1 percent in the 12 weeks to January 4 compared to the same period a year earlier.

It blamed heavy discounting in Britain as well as economic volatility and currency deflation overseas.

Shares in the firm fell 30 percent by 0820 GMT, wiping about 112 million pounds ($180 million) from its market value.

"As a result of lower UK sales and margin and the international currency impact, full year profits are likely to be below the current range of market expectations," chief executive Simon Calver said in a statement.

Analysts had expected Mothercare to post pre-tax profit of 16 million pounds according to a ThomsonReuters consensus forecast.

Mothercare is in the middle of a turnaround plan to try to restore the UK business to profitability.

Figures released on Wednesday showed that high street stores offered their biggest pre-Christmas discounts in at least seven years last month.

Debenhams (>> Debenhams Plc) warned of a sharp fall in profit after its price cuts failed to spur a surge in last-minute Christmas shopping, with Marks and Spencer (>> Marks and Spencer Group Plc) likely to report its tenth consecutive fall in like-for-like sales on Thursday.

Other retailers - such as Next (>> NEXT plc), which did not offer heavy discounts - have fared better.

(Reporting by Christine Murray and Sarah Young; Editing by Neil Maidment and Louise Ireland)