Rising tensions over eating beef in Hindu-majority India are starting to hit the multi-billion dollar buffalo meat trade, with exports falling in the last six months as traders run short of supplies and China lifts purchases from Brazil.

Religious activists, who critics say have been emboldened by nationalist premier Narendra Modi's ascendance, have stepped up attacks on the beef industry, alleging that cows are being killed and falsely labeled for export as buffalo meat.

Cows are revered in Hindu culture and their killing is banned in some states.

Beef exports are banned, but in recent weeks suppliers of buffalo meat have been roughed up by Hindu mobs on suspicion of carrying cow carcasses in their trucks, exporters said.

As a result, the exporters said only a fraction of the meat processing centres authorised to export are operating in the major selling state Uttar Pradesh, where a mob of Hindus lynched a Muslim man last month over rumours he ate beef.

"If we get orders there is no supply; if suppliers try to sell, they are harassed," said Mohammed Tauseef, director of Al-Hamd Agro Food Products in Uttar Pradesh.

Days after Modi condemned the murder in Uttar Pradesh, following criticism over rising religious intolerance in India, villagers in Himachal Pradesh state killed another Muslim man for allegedly smuggling cows.

The government, meanwhile, said steps against illegal exports had helped cut shipments.

"There's no concrete information but there has always been a rumour (that cow meat is exported)," junior farm minister Sanjeev Balyan said this month, adding that authorities had been asked to inspect meat and tighten checks at ports.

India is the world's biggest buffalo meat exporter and April-September shipments fell 13.2 percent from a year ago to 598,901 tonnes, although in value terms they plunged 15.5 percent to $1.89 billion, data from the Directorate General of Commercial Intelligence and Statistics showed.

Indian sales have also lost out to Brazil, the world's No.2 beef supplier, due to a sharper depreciation in the real currency that has lost 30 percent this year compared to only 3 percent in the rupee.

"Traditionally Vietnam sources most of its meat imports from India due to the freight advantage," said a Mumbai-based exporter. "(But now) even after factoring in our freight advantage, we can't compete with Brazil."

Several Indian exporters, however, are more worried about what could be permanent setbacks to trade as some politicians even call for a complete ban on the meat export industry, which generated about $5 billion in sales last year.

Maharashtra, controlled by Modi's party and home to India's financial capital Mumbai, this year extended an existing ban on cow slaughter to cover bulls and bullocks, leaving many butchers jobless.

"There is no life in this business," said Tashkil Ahmed Qureshi, director of Al Falah Food Exports.