UPDATE 1-MPS reaps 227 mln euro capital gain from bond swap

(Adds results of offer, capital gains)

MILAN, July 6 (Reuters) - Monte dei Paschi di Siena will make a capital gain of 227 million euros ($279 million) after holders of subordinated debt worth around 1 billion euros took up a swap offer on Friday, in a deal aimed at boosting the bank's core capital.

Tuscany-based MPS, the world's oldest bank, last month had to turn to the Italian government for help to try to fill a capital shortfall mainly due to its exposure to Italian government bonds.

The bond swap, designed to boost its financial strength, offered bondholders a chance to exchange up to 1.25 billion euros in subordinated debt into new senior notes due in 2015.

MPS said on Friday bondholders had agreed to swap a total of around 1 billion euros into around 790 million new notes.

As a result of the offer, the bank said it will register a gross capital gains of around 227 million euros.

Several Italian banks have used buybacks of hybrid or subordinated debt as part of efforts to shore up their capital base as the price at which the bonds are repurchased allows the lender to book a capital gain.

UBS acted as sole structurer for the MPS deal and as joint dealer manager together with Goldman Sachs and MPS Capital Services. ($1 = 0.8126 euros) (Reporting by Valentina Za; Editing by Jane Merriman and Hans-Juergen Peters)