TOKYO, April 15 (Reuters) - Tokyo Electric Power Co will start loading nuclear fuel into reactor No. 7 at its Kashiwazaki-Kariwa power station on Monday, it said in a statement, as it prepares for safety tests seeking to restart the world's biggest nuclear plant.

The Kashiwazaki-Kariwa plant has been offline since 2012 after another Tepco plant in Fukushima was hit by a tsunami a year earlier which led to the shutdown of all nuclear plants in Japan at the time.

Tepco said on Monday that Japan's Nuclear Regulation Authority has granted the company approval to test safety of the Kashiwazaki-Kariwa's equipment, and it plans to begin loading nuclear fuel into reactor No.7 later in the day.

Tepco needs consent from Niigata prefecture, where the plant is located, to resume operations. The prefecture governor said last month more talks were needed over the possible restart, suggesting operations may not resume quickly.

Tepco's shares were 6% up in Tokyo midday trading following the approval, outperforming the Nikkei index which was 1% down. (Reporting by Katya Golubkova; Editing by Michael Perry)