SAO PAULO, May 3 (Reuters) - Facebook Inc's Chief Executive Mark Zuckerberg on Tuesday called for Brazilians to sign a petition or go to Congress to prevent his company's WhatsApp messaging service from being blocked again.

An appeals court overturned a 72-hour suspension of the application on Tuesday after many of the application's 100 million users in Brazil voiced outrage.

"You and your friends can help make sure this never happens again, and I hope you get involved," Zuckerberg wrote on Facebook, encouraging Brazilians to show up in front of Congress at 6 p.m. on Wednesday to join an event to introduce laws preventing Internet services from being blocked. He posted a link to a petition.

(Reporting by Caroline Stauffer; Editing by Daniel Flynn) ((caroline.stauffer@tr.com; +55 11 5644 7726, +55 11 98431 0410; Reuters Messaging: caroline.stauffer.thomsonreuters.com@reuters.net))

Keywords: FACEBOOK BRAZIL/WHATSAPP ZUCKERBERG