UPDATE 1-Italian lender Monte dei Paschi back in the black in Q3

MILAN, Nov 7 (Reuters) - Italian lender Monte dei Paschi di Siena, rescued from the brink of collapse by a state bailout, posted a third-quarter net profit of 242 million euros ($280 million) on Tuesday, returning to the black after a run of heavy losses.

A year earlier, the bank, the world's oldest, had reported a loss of around 1.2 billion euros, brought low by mismanagement, a derivatives scandal and bad debts. Now controlled by the Italian government, its core capital adequacy ratio has rebounded to 15.2 percent, one of the nation's highest.

Monte dei Paschi, which suffered heavy deposit outflows before the bailout, said it had added 1.6 billion euros in fixed-term deposits and current accounts since end-June, bringing the total for 2017 so far to 11 billion euros.

The quarterly profit benefited from a 554 million euro gain on a debt-to-equity swap carried out as part of the bank's rescue, which followed euro zone rules requiring that private investors suffer losses before any state aid is approved.

The conversion of its subordinated debt into shares also helped its net interest income, which rose 5.5 percent in the quarter from a year earlier.

It booked 175 million euros in loan writedowns in the quarter, bringing the total for the first nine months to about 4.8 billion euros.

($1 = 0.8633 euros) (Reporting by Valentina Za; Editing by Mark Bendeich)