US firm Post Holdings is set to buy British cereal company Weetabix in a deal worth $1.8bn (£1.4bn), according to reports.

Post has agreed to take over the food company, famous for its breakfast cereal brands such as Weetabix, Alpen and Ready Brek, a person familiar with the negotiations told Bloomberg.

The deal could be formally announced before US markets open on 18 April, the person added.

Weetabix is 60% owned by Chinese company Bright Food, with the rest owned by Baring Private Equity Asia.

Bright Food acquired the British firm in 2012 with the intention of expanding the Weetabix brand in China, but it failed to build significant market share in the country with consumers there traditionally preferring a hot meal for breakfast over cold cereal.

Weetabix has also faced declining earnings and profits amid a supermarket price war in the UK — the company's biggest market.

It launched an "on the go" breakfast biscuit range in 2014 but pulled them last year after disappointing sales.

"More and more consumers lead busy lives which limit the time available for a formal breakfast occasion and this is driving a rapid growth in 'on the go' breakfasting," Weetabix was quoted as saying by the Financial Times in a 2015 report.

"This has not been a focus of the company historically and it has therefore required a change in emphasis in our innovations programmes."

Weetabix has been made in the UK since 1932 and the company holds a royal warrant from Queen Elizabeth II.

Associated British Foods and Cereal Partners and Italian pasta maker Barilla had been named as other potential suitors for the food company.

Headquartered in Lakeville, Minnesota, Post is the third-largest breakfast cereal company in the US.

It owns brands such as Honey Bunches of Oats, Pebbles, Great Grains, Golden Puffs, Cinnamon Toasters, Oh's, Berry Colossal Crunch and Malt-O-Meal.