TOKYO, Oct 25 (Reuters) - Japanese Finance Minister Taro Aso said on Friday next year's July-September gross domestic product (GDP) will be key in deciding whether to raise the sales tax to 10 percent from 8 percent in 2015.

Speaking at a news conference, Aso also said that consumer prices are gradually rising thanks in part to the government's economic policies.

But he added, "It will take more time for Japan to escape deflation."

Japan will raise the national sales tax to 8 percent from 5 percent in April next year. The government plans to raise the tax rate again to 10 percent in October 2015, although it will make a final decision next year looking at economic conditions.