British American Tobacco PLC said the rapid growth of tobacco-heating products in Japan has slowed, adding to doubts that the category can offset the decline in traditional cigarettes.

Market share gains of BAT's Glo device have stalled over the last seven weeks, after the tobacco-heating product hit a 4.3 percent share of Japan's tobacco market during its first six months on the market, the London-based company said Tuesday.

The slowdown in sales casts doubt on the company's ambition of more than doubling its revenue from cigarette alternatives to "substantially more" than £1 billion ($1.34 billion) this year.