The sale of one of Norfolk’s largest agricultural supplies businesses has taken a step forward after being cleared by the Office of Fair Trading (OFT).

In January, the owners of Great Yarmouth-based fertiliser producer J&H Bunn entered “exclusive negotiation” with Koch Fertilizer over the sale of the company, one of East Anglia’s largest with a turnover in excess of �140m.

Founded in 1816, the company has an 18pc share in the UK fertiliser market and employs about 150.

The clearance by the OFT lifts one of the final hurdles for the sale to Koch Fertilizer, a subsidiary of US giant Koch Industries, one of the world’s largest private companies.

Koch has pledged to retain all of Bunn’s 150-strong national workforce and expand the business, and it is thought the 50 staff at Yarmouth could eventually grow to at least 75.

The value of the proposed sale has not been made public but is expected to be an eight-figure sum.

In addition to the main J&H Bunn operation, the acquisition will see Koch take over seven regional subsidiaries and brands in East Anglia, Humberside, Teesside and Scotland. They include Yarmouth haulage contractors Spandler Brothers.

Bunn supplies more than 10 million tonnes of fertiliser annually. In its latest accounts for the year to March 31, 2010, the company reported turnover of �141.6m, down from �175.9m the previous year, reflecting drops in world fertiliser prices, which have since recovered.

Profit before tax dipped from �11.8m to �7.7m over the period. No one from the company was available to comment.