BEIRUT, Lebanon  Demonstrators blocked roads and held rallies on Monday in Oman, a normally quiet oil-rich country along the southeastern coast of the Arabian Peninsula, as three-day protests calling for political reforms and better living conditions spread to Muscat, the capital.

The protests in Oman, the latest country to join the wave in the Arab world, highlight the depth of discontent against long-serving dictators and monarchs. It also suggests that demonstrations could spread to other Persian Gulf countries.

In the northeastern port city of Sohar, where the protests originated, demonstrators blocked roads to the port, Oman’s second biggest, and to an industrial area that includes a refinery and an aluminum factory, two witnesses in Sohar and news agencies said. They also set a supermarket on fire and clashed with the police.