* Toshiba, TEPCO, JBIC to sell back convertible debentures
* Deal struck after Uranium One agreed to buyout by ARMZ
* Uranium One to pay C$271.79 mln, 101% of original value
* Companies to receive 11-year purchase rights
* Toshiba shares end down 1.6 pct, TEPCO up 0.2 pct (Recasts, adds details)
TOKYO, Aug 9 (Reuters) - Japan's Toshiba Corp (6502.T) and Tokyo Electric Power (TEPCO) (9501.T) said on Monday they will sell back their convertible debentures in Uranium One UUU.TO for $265 million after the Canadian uranium producer agreed to a buyout offer by a Russian miner.
The two companies, along with Japan Bank for International Cooperation (JBIC), will still have rights to buy as much as 2.5 million pounds (1.13 million kg) of natural uranium a year from Uranium One from 2014 to 2025, they said in a statement.
Uranium is the most commonly used nuclear energy source.
Russian state-owned miner ARMZ is in the process of taking a controlling stake in Uranium One in exchange for stakes in two mines in southern Kazakhstan. [ID:nSGE66E0LP][ID:nN08246560]
Nuclear power plant maker Toshiba, Asia's biggest utility TEPCO and state-owned JBIC will sell back Uranium One's convertible debentures for C$271.79 million, equal to 101 percent of the C$269.1 million they paid in January 2010.
The companies originally owned rights to buy up to 20 percent of Uranium One's annual production.
Before the announcement, Toshiba shares closed down 1.6 percent at 437 yen, while TEPCO stock ended up 0.2 percent at 2,420 yen. The benchmark Nikkei average .N225 dropped 0.7 percent. (Reporting by Yumiko Nishitani and Sachi Izumi; Editing by Joseph Radford)