MESTRE, Italy, May 25 (Reuters) - Sales at Italian department store chain Gruppo Coin SpA (GCN.MI) fell slightly year-on-year in the three months to April, as rain kept customers at home, although the trend changed in May, its top executive said on Monday 25 May.

Gruppo Coin flagship store in Milan

Starting from May, sales are "sharply growing and at the moment we are in line with our budgets and plans", Chief Executive Stefano Baraldo told a news conference.

On a possible tie-up with rival Upim, controlled by Pirelli & C Real Estate (PCRE.MI) unit Rinascente, Baraldo said Coin was still interested, although "there are no talks ongoing".

On Coin's expansion plans, Baraldo said he expects 20 new stores to open outside Italy by the end of the year.

In the fiscal year to end-January, Coin's net sales fell 2.3 percent to 1.145 billion euros ($1.6 billion). It posted a net profit of 38.2 million euros. ($1=.7145 Euro) (Reporting by Carlo Saccon; writing by Danilo Masoni; editing by Simon Jessop)