TOKYO, May 30 (Reuters) - Japan's Nikkei share average tumbled to six-week lows on Wednesday morning after political turmoil in Italy sparked concerns about the stability of the euro zone, hurting most sectors on the board.

Traders said they expected the Bank of Japan to buy exchange-traded funds to support the market amid the morning weakness. The BOJ had bought ETFs for five straight sessions up until Tuesday as part of its wider policy of supporting asset prices in the economy.

The Nikkei dropped 1.4 percent to 22,043.53 in midmorning trade, after falling to a six-week low of 21,931.65. The Nikkei managed to stay above its 75-day moving average of 21,920.77, which has become the index's immediate support level.

Sources close to some of Italy's main parties said Italy may hold repeat elections as early as July after the man asked to be prime minister failed to secure support from major political parties for even a stop-gap government.

The political crisis in Rome, and the threat to the euro project it represents, triggered a rush to safe havens like U.S. debt and the Japanese yen.

"The Italian political problems triggered global investors' risk-off stances. Exporters and financials are hard hit and they will likely remain vulnerable," said Norihiro Fujito, senior investment strategist at Mitsubishi UFJ Morgan Stanley Securities.

Insurers and banks, which have invested in higher-yielding foreign bonds due to low yield environment in Japan, underperformed and stumbled 3.0 percent and 2.5 percent, respectively.

Sompo Holdings shed 2.6 percent, Dai-ichi Life Holdings declined 4.2 percent. Mitsubishi UFJ Financial Group dropped 3.4 percent and Sumitomo Mitsui Financial Group declined 2.6 percent.

U.S. benchmark 10-year Treasury yields on Tuesday posted their largest one-day drop in nearly two years.

Exporters were under pressure as the dollar slipped 0.3 percent to 108.38 yen, edging towards a five-week low of 108.115 yen hit the previous day. Toyota Motor Corp dropped 2.1 percent, Mazda Motor Corp stumbled 3.0 percent and Hitachi Ltd shed 3.0 percent.

The broader Topix dropped 1.6 percent to 1,734.08.

(Editing by Sam Holmes)