LONDON, June 25 (Reuters) - Britain's Brexit minister David Davis said on Sunday he was "pretty sure" he could negotiate a good deal to leave the European Union, something that would require a transitional arrangement for around one or two years.

Asked whether he was sure there would be a Brexit deal, Davis told the BBC's Andrew Marr Show: "I am pretty sure, I am not 100 percent sure, it's a negotiation ... You can be sure there'll be a deal, (but) the deal I want is the free trade agreement, the customs agreement and so on.

"I said it will be turbulent, there will be difficulties, but at the end of the operation there is a point of common interest in both sides, where we gain by being able to exploit global markets, where they gain by having a friendly and comfortable ally, not an irritating member of the club."

(Reporting by Elizabeth Piper; editing by Mark Heinrich) ((elizabeth.piper@thomsonreuters.com; 07979746994; Reuters Messaging: elizabeth.piper.thomsonreuters.com@reuters.net))