Uniqlo operator Fast Retailing has kept its yearly forecast unchanged, even as business in the key market of mainland China was hit by virus restrictions.

The Japanese casualwear behemoth posted better-than-expected sales and profit in the three months to December, thanks to the growing diversification of its business.

The company does not expect the spread of the highly contagious Omicron coronavirus variant to dent overall performance in 2021-22. However, it sounded a note of caution over the unpredictable impact of the pandemic.

Net profit for the first quarter jumped 33 percent on-year to 93.6 billion yen ($817 million) marking its best ever first quarter, Fast Retailing said, as business in many parts of the world rebounded from virus lockdowns.

However, revenue and profit declines were seen in mainland China, which is pursuing a strict zero-COVID strategy and has imposed tough localised restrictions in recent months.

Sales dropped in Japan, too, following strong performance the previous year and as warm autumn weather hit demand for winter outfits.

The company, one of the world's top aooarel retailers, kept its net profit forecast for the year to August 2022 unchanged at 175 billion yen -- a three-percent increase from the previous year's record figure.

Its results have also been boosted by the depreciation of the yen, which recently hit a five-year low against the dollar.