By Ellen Wulfhorst

NEW YORK, May 3 (Thomson Reuters Foundation) - Roughly one in three people in the Middle East and North Africa has recently paid bribes to public officials and for services such as medical care and electricity, and most people say corruption is growing, a watchdog group said on Tuesday.

Only a fifth of people who paid a bribe reported the incident, and twice as many said they suffered retaliation when they did report corruption, according to Transparency International.

Bribery is common in obtaining public services, in the court systems and among police in the region, research by the Berlin-based anti-corruption group found.

People reported paying bribes as well for medical services, identity documents, permits, electricity and water, it said.

Transparency International interviewed nearly 11,000 adults from September 2014 to November 2015, in Algeria, Egypt, Jordan, Lebanon, Morocco, Palestine, Sudan, Tunisia and Yemen.

Nearly one in three people said they had paid a bribe for public services in the 12 months prior to the survey - amounting to about 50 million people, it said.

The bribery rate was highest in Yemen, where four out of five people reported paying a bribe for public services.

The study said while dissatisfaction with corrupt leadership has helped fuel political change in the region, especially the Arab Spring protests that began in 2010, corruption persists.

Two-thirds of people perceive corruption to have risen in the 12 months prior to the survey, particularly among government officials, tax officials and judges, it said.

"The extent of the bribery reported in our survey is a major cause for concern, as widespread corruption is linked to governmental institutions that are inefficient and distrusted," the study said. "Corruption also leads to an unfair distribution of services and undermines law and order."

Despite the findings, across the Middle East and North Africa, slightly more than half the people said they think ordinary citizens could make a difference by reporting corruption and refusing to pay bribes, the study said.

Residents of Tunisia were most optimistic and residents of Lebanon least so, it said.

Yet a third of people overall said they feared retaliation if they reported corruption.

All of the governments except Sudan were rated badly at fighting corruption by a majority of citizens, the research said. The question was not asked in Sudan due to recent elections, it said.

Transparency International called upon governments to prosecute corruption, allow for freedom of the press, establish independent anti-corruption commissions, make officials disclose holdings, enact codes of conduct and protect whistleblowers.

"Only if governments in the region are ready to make a fundamental shift in their mindset to allow for meaningful participation by citizens and civil society in public life, and stop using repression or intimidation against them, will the fight against corruption stand a chance," the study said.

Overall, Egypt, Jordan and Tunisia got the most positive ratings, while Algeria, Morocco, Sudan and Palestine fell in the middle, and Lebanon and Yemen got the worst ratings, it said.

(Reporting by Ellen Wulfhorst, editing by Alisa Tang. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, property rights and climate change. Visit news.trust.org)