TOKYO, Aug 29 (Reuters) - Japan's Nikkei share average advanced to a two-week high on Tuesday, buoyed by overnight gains in Wall Street, although continued concerns about China limited the upside.

The Nikkei rose as much as 0.68% to 32,389.12 early in the session, its highest since Aug. 15, before entering midday recess at 32,225.72 as Chinese markets opened weaker.

The broader Topix, meanwhile, eked out a 0.05% gain.

Nomura Securities strategist Kazuo Kamitani said the 25-day moving average at around 32,276 is proving to be a firm barrier to further gains.

"It's an environment where traders' attention is easily drawn to the 25-day moving average, and on the question of whether a break higher is likely in the next couple of days, it's more likely the Nikkei will stay below it," he said.

Above 32,300 in particular, "the market feels quite heavy," Kamitani added.

Of the Nikkei's 225 components, 130 rose and 92 fell, with three flat.

Overnight, the three main Wall Street indexes all gained 0.6% or more.

However, an index of Chinese blue chips opened lower on Tuesday, although it eventually recovered to be up about 0.5%.

The previous day, a raft of stimulus announcements boosted the index by 5.5% at one point, although the rally had fizzled to just 1.2% by the close.

Tokyo Electric Power Co was the Nikkei's top performing stock by far, rallying 5.58%.

The utility has been releasing treated radioactive water into the Pacific Ocean, taking it into the final phase for decommissioning the wrecked Fukushima reactor. Testing of seawater and marine life has so far found no abnormalities.

Rakuten Group was another standout, gaining 2.36%. CEO Hiroshi Mikitani wrote on X (formerly Twitter) that mobile phone subscriptions had topped 5 million.

Toyota Motor, meanwhile, eased 0.39% after the automaker suspended operations at domestic plants due to a system failure.

Chipmaker Renesas Electronics sank 1.63% to be the Nikkei's worst performer, giving back part of Monday's 4.43% jump, its best day in about a month. (Reporting by Kevin Buckland; Editing by Varun H K)