BUCHAREST, Romania - Thousands of angry shepherds engaged in a tense standoff with riot police outside Romania's parliament building Tuesday in protest at a law that restricts the number of sheepdogs they can use and bans them from grazing sheep during the winter.

Romanian authorities say the Carpathian shepherd dogs are aggressive and kill other wild animals such as deer and wild boar that are hunters' favorites, while the grazing ban helps the environment. But shepherds insist the law is an attack on centuries of sheep-rearing in the rural Balkan nation.

Riot police fired tear gas at the shepherds, some of whom were dressed in floor-length sheepskins and were blowing horns, to keep them from charging at the Parliament building. There was a tense standoff lasting until nightfall between hundreds of riot police, some mounted on horses, and the 4,000 shepherds. Some had traveled as far as 300 miles for the protest, but they didn't bring their dogs.

Alarmed by the unprecedented protest, the Senate chairman called Prime Minister Dacian Ciolos and asked him to modify the law in an emergency ordinance. Ciolos explained that was not immediately possible as the law had been voted on by Parliament, spokesman Dan Suciu said. The prime minister has promised to try to find a legal solution, Suciu said.

Lawmaker Liviu Harbuz later said a parliamentary committee had signed an agreement that will allow the government to adopt an emergency ordinance scrapping the regulation of sheepdogs and grazing.

The contentious law, passed in June, says shepherds can use a single sheepdog for sheep grazing on the plain, two for hilly terrain and a maximum of three for mountain flocks. If shepherds flout the law, extra dogs can be shot. It also bans grazing from December to April.

"A lot of dogs will be killed and this will endanger the sheep," Ionica Nechifor, general secretary of the Romovis sheep farming federation, told The Associated Press by telephone. He said shepherds need 10 dogs for mountain flocks and an average of five to six for sheep grazing on the plain.

The law was introduced by supporters of hunting, a popular pastime among Romania's elite since the days of Communist leader Nicolae Ceausescu. He was an avid hunter, but according to accounts, not an accurate shot. Security officers hid in the bushes and undergrowth and killed the animals for him.

Ceausescu was toppled and executed during the December 1989 revolution, but in part thanks to Romania's large swaths of forests and plains, the pastime remains popular among the well-heeled, who associate it with the aristocracy.

Sheep farming forms the backbone of rural Romania, home to some 10 million sheep and 1.5 million goats. Supporters of the law have argued that it will protect animals targeted by hunters from the large Carpathian shepherd dog, a large indigenous canine, and that by keeping the sheep off the pastures will protect the environment.

Shepherds vehemently disagree. "We can't live without sheepdogs, which scare off the wild animals," said Traian Nica, a 49-year-old shepherd. "We want our rights back."

Grigore Popa, 68, waved a big stick and shouted: "I was born among the sheep and we will cut lawmakers' heads off."

Agriculture Minister Achim Irimescu said Tuesday he supported the shepherds' demands and the law needed to be changed, in an interview with Digi24 television station.