* Mining stocks outperform on rising oil prices
* Tepco falls after govt doubles Fukushima-related costs
By Ayai Tomisawa
TOKYO, Dec 9 (Reuters) - Japanese stocks rose to their highest level in a year on Friday morning, supported by Wall Street gains and solid buying of exporters on the back of a weaker yen.
The mining sector was the top gainer on the board, rising 2.8 percent after oil prices extended a rally on Friday, buoyed by growing optimism that non-OPEC producers might agree to cut output following a cartel agreement to limit production.
Inpex Corp soared 2.8 percent and Japan Petroleum Exploration Co jumped 4.1 percent.
The benchmark Nikkei gained 1.1 percent to 18,970.98 in midmorning trade, after earlier jumping to 18,983.47, the highest level since December 2015.
For the week, the index is poised to rise 3 percent for its fifth straight weekly gains.
U.S. shares set fresh record highs overnight as a month-long rally following Republican Donald Trump's election win on Nov. 8 rolled on.
"The U.S. market seems to be the only market still enjoying a Trump rally," said Eiji Kinouchi, chief technical analyst at Daiwa Securities. "U.S. market's strength is giving a boost to Japanese shares."
The dollar was firm at 114.070 yen. Bellwether stocks took the cue of a weaker yen and rose sharply, with Sony Corp up 3.2 percent, Nintendo Corp 3.0 percent higher and TDK Corp up 1.7 percent.
Tokyo Electric Power Co, reversed earlier gains and fell 3.7 percent after Japan's trade ministry said it has nearly doubled its projections for costs related to the Fukushima nuclear disaster to 21.5 trillion yen ($188.40 billion).
The broader Topix gained 0.6 percent to 1,521.33 and the JPX-Nikkei Index 400 advanced 0.6 percent to 13,623.93.
Editing by Shri Navaratnam