NEW DELHI - India has asked utilities to import 6% of their coal requirement until March, due to rising power demand and inadequate supply of domestic coal, the power ministry said.

Worries have mounted over shrinking coal stocks at power plants, where inventories fell the fastest in two years during the first half of October.

In a letter dated Wednesday and seen by Reuters on Saturday, the ministry asked the companies to blend the imported coal with domestic coal to maintain stocks amid higher consumption.

"The Gencos (utilities) may continuously review their stock position and opt for blending as per the requirements if the shortfall in domestic coal supply is more than 6%," the letter said.

(Reporting by Sudarshan Varadhan; Writing by Neha Arora; Editing by William Mallard)