MILAN (Reuters) - Roberto Mancini will remain Inter Milan coach despite constant speculation linking Jose Mourinho with the job, chief executive Ernesto Paolillo said on Thursday.

"We have the best coach in Italy with Robert Mancini," Paolillo told Web site www.arabianbusiness.com in an interview.

"We have a long contract with him, we're completely satisfied with him. He was the winner last year and two years ago, and is winning this year - why do we have to change?"

Inter can retain their Serie A title by beating rivals AC Milan on Sunday before facing Lazio in an Italian Cup semi-final second leg on Wednesday.

Mancini announced after Inter's Champions League first knockout round defeat by Liverpool in March that he would quit at the end of the season.

He changed his mind the next day but media reports have speculated he will still leave at the end of the campaign because of strained relations with club owner Massimo Moratti.

Former Chelsea coach Mourinho has denied that he is on his way to Inter amid constant rumours in the European press.

Paolillo also said Inter needed investment to compete with English clubs in Europe but was coy about a move for Barcelona's Ronaldinho, whom Moratti and AC Milan chief executive Adriano Galliani say is too dear at 40 million euros (31.7 million pounds).

"If we don't buy Ronaldinho it's not because it's costing a lot, it would be because we have to buy what we need. The role of Ronaldinho is well covered in our team. Even if the price is lower, it's the role of the player we're looking at," he said.

"We have a very good team but we need two or three more players to be competitive with Manchester United, Chelsea and Liverpool. To win (the Champions League) you must be the strongest."

(Writing by Mark Meadows, editing by Ken Ferris)