Wearing face masks and white clothes, people from Ethiopia's Oromo nation descended on the capital Addis Ababa to mark the annual Thanksgiving festival known as Irreecha on Saturday.

The crowds were significantly smaller due to political tensions and the COVID-19 pandemic.

Hundreds of people were arrested ahead of the festival, some accused by authorities of plotting terror attacks and a new wave of unrest.

"The reason there are few people this year is because it is better for our health and peace. And for that reason the only people invited are the ones observing the celebration. That way people can protect themselves from COVID-19 while celebrating the holiday. We are observing the holiday respecting the directives announced by the government", said Edelawit Alemayehu, one of the festival goers. 

Security was tight with event goers subjected to at least six security checks complete with body searches and, in some areas, sniffer dogs.

The festival usually attracts hundreds of thousands of people, but only a few thousand were allowed to attend this year.

The Oromo, while being the country's largest ethnic group, traditionally have expressed frustration over perceived marginalization.

Prime Minister Abiy Ahmed is the country's first Oromo leader, but he faces growing criticism by some Oromo that he hasn't done enough for them.

The Irreecha festival marks the end of the rainy season and the start of the harvest.