LOS ANGELES (Reuters) - Burger King Holdings Inc expects lower fiscal third-quarter revenue and restaurant margins in the US and Canada as bad weather in the central and eastern United States kept diners away.

The Miami-based hamburger chain added that sales and traffic trends are better this month, helping to lift shares one percent.

"We have seen improvement in sales with positive traffic at our company-owned restaurants in the US and Canada during the first week of March, compared to January and February, as the impact of weather has become less significant," chairman and chief executive officer John Chidsey said in a statement.

The fast-food chain operator said yesterday over 75 percent of its US and Canada segment's restaurants are located in those regions and said the segment's comparable-system sales fell 8.2 percent in January and February from a year earlier.

Burger King estimated the weather reduced January and February US and Canada system comparable sales by about three percentage points.

On Monday, archrival McDonald's Corp said February sales at restaurants open at least 13 months rose 0.6 percent in the United States. That improved from January, when US same-store sales fell 0.7 percent.