A sign is seen at an AstraZeneca site in Macclesfield, central England May 19, 2014. . REUTERS/Phil Noble

LONDON (Reuters) - AstraZeneca AZN.L is selling three older drugs for asthma and rhinitis for at least $350 million as the company continues a strategy of divesting assets and investing in its pipeline of new medicines.

Covis Pharma will pay AstraZeneca $350 million for rights to Alvesco, Omnaris and Zetonna, plus conditional sales-related payments of up to $21 million over four years from 2019. Swiss-based Covis already markets the drugs in the United States.

AstraZeneca said on Tuesday the deal was expected to close by the end of 2018 and the payments would be booked as other operating income, which will not affect financial guidance for the year. The three drugs had combined sales in 2017 of $106 million.