* Nikkei on track to post biggest gain in 2 months
* Mitsubishi Motors sags on compensation cost concerns
By Ayai Tomisawa
TOKYO, June 20 (Reuters) - Japan's Nikkei share average soared to a near one-week high on Monday morning as worries that Britain might leave the European Union receded after weekend polls showed the campaign to keep the country in the EU regaining momentum.
The Nikkei rose 2.4 percent to 15,966.72 after rising to as high as 16,035.44, the highest since June 14. It is on track to post the biggest daily percentage gain in two months.
Three British opinion polls ahead of the EU membership referendum on June 23 showed the "Remain" camp recovering recent lost ground, although the overall picture remained one of an evenly-split electorate.
Sterling rallied early on Monday, helping underpin risk sentiment, which in turn weighed on the safe-haven yen.
"Those who were risk averse are reversing their positions," said Yoshinori Shigemi, global market strategist at JPMorgan Asset Management.
"Sentiment was extremely negative last week, but it's recovering now, though we should not be overly optimistic."
All of Topix's 33 subsectors were in positive territory.
Exporters gained ground, after the dollar climbed 0.6 percent to 104.68 yen. Toyota Motor Corp surged 2.3 percent, Honda Motor Co soared 2.4 percent and Panasonic Corp jumped 2.7 percent.
Financials also attracted buyers, with Mitsubishi UFJ Financial Group gaining 3.0 percent, Sumitomo Mitsui Financial Group rising 3.2 percent and Nomura Holdings up 3.2 percent.
Underperforming the market was Mitsubishi Motors Corp , which fell 3.5 percent after the company announced on Friday a reimbursement programme of at least $600 million to compensate owners of some of its mini-vehicles for overstating fuel economy specifications.
The broader Topix gained 2.2 percent to 1,278.37 and the JPX-Nikkei Index 400 rose 2.2 percent to 11,518.70. (Editing by Sam Holmes)