Among the approved measures are a prohibition on certain cigarette ingredients, such as menthol, and a requirement to increase the anti-tobacco messages printed on packs.

The company, one of Chile's largest cigarette manufacturers, called the changes to the law "arbitrary and unconstitutional," and said the measures would cost the government $400 million (260 million pounds) in annual tax revenue.

The local unit will shut operations in four of Chile's regions and lay off at least 20 percent of its workforce as a result. It said it will consider shutting another plant located some 50 miles west of capital Santiago.

"We want to express that we deeply lament that the Senate approved this, a decision which will affect thousands of Chileans that have worked legally and responsibly in this sector for more than a hundred years," BAT added.

(Reporting by Gram Slattery; Editing by Andrew Hay)