Four major banks will extend uncollateralized loans to Tokyo Electric Power Co. for the first time since the March 2011 nuclear disaster started at the utility's Fukushima No. 1 power plant, sources said Tuesday.

Sumitomo Mitsui Banking Corp., Bank of Tokyo-Mitsubishi UFJ, Mitsubishi UFJ Trust and Banking Corp. and Sumitomo Mitsui Trust Bank Ltd. plan to resume such loans to refinance ¥65 billion in borrowing by the utility, which falls due at the end of April, the sources said.

The banks, however, plan to limit the period for the uncollateralized loans to six months to mitigate the risk they will become uncollectible, they said.