NEW DELHI, April 13 (Reuters) - India has extended a mandate on imported coal-based power plants to operate at full capacity until Oct. 15 to meet anticipated high demand for electricity in the summer months, according to a government order seen by Reuters.

The order, dated Friday, invoked an emergency clause available to the government in directing the companies, including Tata Power and Adani Power, operating such imported coal fired plants with a capacity of nearly 16 gigawatts to continue operations.

The order is not yet public. The plants were initially allowed to operate until June 30.

The South Asian nation registered an 8% rise in electricity consumption in the financial year that ended last month, and demand is expected to rise in the hot summer months. (Reporting by Sarita Chaganti Singh; Editing by William Mallard)