Philip Morris International Inc faces the possibility of having imports of its IQOS heated-tobacco sticks to the US blocked as early as November, in an intensifying legal battle with British American Tobacco Plc over cigarette alternatives.

BAT’s subsidiary Reynolds American Inc seeks to block imports of the sticks, as it alleges that the tobacco heating technology used in IQOS devices infringed its patents. The six-day trial at the US International Trade Commission in Washington, DC began on Monday, with a judge scheduled to release his findings in May.