PARIS, May 11 (Reuters) - Panama, rocked by a recent major tax scandal, has joined around 100 countries in an agreement to share financial information automatically to tackle tax evasion, the Organisation for Economic Cooperation and Development said on Wednesday.

The information sharing scheme was already in the works when Panama came under pressure after the leak of thousands of confidential documents from a Panamanian law firm in April showed their failure to cooperate in global efforts to clamp down on tax evasion by the rich and powerful.

Bahrain, Lebanon, Nauru and Vanuatu are also signing up to the agreement on automatically swapping tax information, which around 100 countries have now joined. Such exchanges are expected to start in September 2018, the Paris-based OECD said.

"These political commitments to join the fight against tax evasion must be turned into practical reality, through implementation of the standards and actual exchange of information," OECD chief Angel Gurria said in a statement.

(Reporting by Michel Rose; Editing by Raissa Kasolowsky) ((michel.rose@thomsonreuters.com; +33149495071; Reuters Messaging: michel.rose.thomsonreuters.com@reuters.net; Twitter handle: @michelreuters))