TOKYO, Sept 1 (Reuters) - Japanese shares jumped on Wednesday, with the Nikkei hitting 1-1/2-month highs, as investors bet Prime Minister Yoshihide Suga's manoeuvring may help to diminish potential concerns about the country's political stability.

The Nikkei average gained 0.89% to 28,337.71 by 0148 GMT, rising above a key resistance from its 200-day average at 28,281 and hitting its highest level since mid-July.

Another resistance from the Ichimoku cloud top loomed at 28,405, although a clear break there could cement a bullish mood.

The broader Topix rose 0.81% to 1,976.58, touching its highest level since mid-June.

PM Suga intends to dissolve the lower house of parliament in mid-September after a reshuffle of the ruling party executive and his cabinet next week, Mainichi newspaper said.

The prospects of a parliamentary dissolution are seen as positive as the market, historically, has performed well after the parliament was dissolved.

Polls show Suga remains unpopular but not enough to let opposition parties defeat the ruling coalition.

"While things seem very fluid, some people think that political uncertainty has diminished on the ground that Suga is likely to win the upcoming ruling party leadership election," said Naoya Oshikubo, senior strategist at Sumitomo Mitsui Trust Asset Management.

"In addition, coronavirus cases in Japan have been falling recently, raising hopes about eventual lifting of state of emergency," he added.

Investors, who had shorted Japanese stocks on political and coronavirus worries, covered their positions.

Komatsu jumped 4.4% after Bloomberg reported Cathie Wood's Ark Autonomous Technology and Robotics ETF has been buying the firm's American depository receipts almost daily since mid-August.

Komatsu is now the 13th largest holding for the popular fund, its disclosure documents showed.

Toyota Motor rose 0.4% to recover to its levels before the carmaker's shock announcement on Aug. 19 that it will slash production by 40% in September. (Reporting by Hideyuki Sano; editing by Uttaresh.V)