SAO PAULO, May 18 (Reuters) - Shares in Brazilian meatpackers slid on Tuesday after their operations in Argentina were hit with a 30-day beef export ban in that country, as Buenos Aires struggles to rein in rampant inflation.

The decision mainly affects Brazil-based Marfrig and Minerva, which have multiple plants there.

Minerva will potentially be most affected because its operations in Argentina represent about 10% of global sales, said Rodrigo Brolo, head of agribusiness advisory at Criteria Investimentos.

Minerva's potential use of Brazil as an alternative export base is not so simple, Brolo said, because Argentina's cattle and cuts sold by the company from there are different.

The ban unveiled on Tuesday unnerved Argentine farm groups, which said they would halt trading of livestock in protest against the move to tamp down high inflation.

Alcides Torres, director at consultancy Scot, said Brazil could benefit from Argentina's beef export ban because buyers like China could look for other suppliers.

But Lygia Pimentel, a director at consultancy Agrifatto, told Reuters that a potential rise in demand for Brazil's beef could put even more pressure on cattle prices, which are already squeezing local meatpackers.

Marfrig shares, which had fallen almost 3% intraday, closed 1% lower after the company said in a securities filing that the ban would hit 1.3% of its overall net revenue. The company is the largest provider of beef products in Argentina, where it has five plants and sells under the Paty hamburger brand.

Shares in Minerva, which owns five plants and one distribution center in Argentina, closed 3.5% lower. Like rival JBS SA, off almost 3%, it was one of the biggest losers on the São Paulo stock exchange.

Minerva, which agreed to buy certain Argentine plants from bigger rival JBS in 2017, said it will continue serving clients in export markets via Uruguay, Paraguay, Brazil and Colombia.

It emphasized its strong presence in Argentina, where it owns the Swift brand. (Reporting by Nayara Figueiredo and Ana Mano in São Paulo; Writing by Ana Mano; Editing by Dan Grebler)