ATHENS, Oct 26 (Reuters) - Piraeus Bank, one of Greece's four largest banks, said on Monday it had no imminent plans for a share capital increase after reports that three of its shareholders proposed such a move.

Piraeus's shares fell 24% on the Athens Stock Exchange after Greek media reported that three of its shareholders, which own a total of 19.8% in the bank, proposed a capital increase of 800 million euros ($945.36 million).

"Piraeus Bank would like to inform the investment community that ... there are no plans to proceed with a share capital increase in the foreseeable future", it said in a stock exchange filing.

It said that it has been exploring all relevant options to accelerate "the derisking of its balance sheet".

Traders said the shares fell because a rights issue would mean significant share dilution for retail shareholders.

Piraeus Bank is 26.4% owned by Greece's bank rescue fund, the Hellenic Financial Stability Fund (HFSF).

($1 = 0.8462 euros) (Reporting by Angeliki Koutantou. Editing by Jane Merriman)