* Brazil says no grounds for restrictions on its beef
* Several countries limiting imports since atypical BSE case
* OIE commends Brazil for reporting rare, spontaneous case
By Gus Trompiz
PARIS, Dec 21 (Reuters) - The world's top beef exporter, Brazil, will give countries that curbed imports of its beef after a case of mad cow disease until March to drop the measures or it will file a complaint at the World Trade Organisation, farm ministry officials said.
Five countries have implemented full or partial bans on Brazilian beef imports since confirmation this month of a case of atypical bovine spongiform encephalopathy (BSE), or mad cow disease, in a cow that died in 2010.
Atypical BSE cases can occur spontaneously in elderly cattle and the 13-year-old animal in the Brazilian case never developed full-blown BSE, testing instead positive for a protein that is the causal agent of mad cow disease.
Brazil had previously launched a diplomatic offensive to fend off restrictions over the death of the cow in the southern state of Parana which was confirmed only this month by Brazilian authorities.
But now Brazil has promised to take retaliatory action against countries rejecting its beef, saying there are no grounds for such action.
"March is the deadline," said Enio Marques Pereira, Secretary for Animal and Plant Health at Brazil's farm ministry, after a meeting at the World Organization for Animal Health (OIE) headquarters on Friday.
Officials stressed Brazil has kept its status as a country presenting negligible BSE risk under an OIE classification, and that OIE norms consider safe for consumption products like red meat and gelatine, even when BSE has been declared in a country.
The Brazilian cow in question never entered the food chain.
Countries restricting Brazilian beef include Egypt and Saudi Arabia which rank among Brazil's top 10 beef buyers, but Marques said the economic impact so far was "very low", noting that Egypt was only banning meat from the region where the BSE case occurred. Saudi Arabia has suspended Brazilian beef outright.
The other countries which have imposed temporary bans are South Africa, Japan and China.
The OIE welcomed the fact that Brazil had managed to detect the atypical case in a national herd of more than 200 million, though logistical problems at a laboratory delayed the analysis of the animal's tissue since its death in 2010.
"We're rather reassured by the fact that Brazil reported this case," Bernard Vallat, director general of the OIE, said.
He stressed that an end to the use of cattle feed containing matter from ruminant animals had succeeded in nearly eradicating BSE after tens of thousands of cases in the 1980s and 1990s, mostly in Britain. (Editing by Peter Murphy and Keiron Henderson)