SANAA - A man convicted of raping and murdering a three-year-old girl was executed in the Yemeni capital Sanaa on Monday in front of hundreds of onlookers, the first public execution there since 2009.

"Security was very tight, because authorities were fearing a revenge attack by armed men from the Bani Matar tribe to which the girl's family belong," said Reuters photographer Khaled Abdullah who witnessed the scene.

The police van transporting Muhammad al-Maghrabi, 41, to Sanaa's Tahrir Square was escorted by five police patrol vehicles. The execution drew a large number of onlookers, some perched up telegraph poles and many watching from rooftops.

The crowd started to shout "Allah is the greatest" when Maghrabi arrived.

"The man was escorted from the van to the middle of the square, and then the place turned to a complete chaos and I fought for a position to take pictures," Abdullah said.

"He tried to talk to the executioner, a police officer who was calmly smoking a cigarette as he stood next to him before pointing his AK-47 to his back from a very close distance.

"Soon he fired around four shots, and people realized that it was done, they rushed to the place and tried to take the body, but the police were able to take the body to the van and drove through the crowd out of the square."

Yahya al-Matari, the father of the murder victim, Rana al-Matari, told reporters after the execution he was satisfied.

"This is the first day in my life," he said. "I am relieved now."

Yemen has been devastated by more than two years of civil war between its Saudi-backed government and Houthi fighters who seized parts of the country in 2014 and 2015.