At least three Yemeni soldiers were killed on Friday after an explosion in the southern port city of Aden.

The blast in Aden's free-trade zone came after Yemeni security forces opened fire on thousands of people gathered nearby for a funeral, killing at least one person. The violence wounded at least six other people Friday.

Since January, thousands of people across the country have been calling for an end to President Ali Abdullah Saleh's autocratic rule. Many of the protests have turned violent, with security forces killing at least 200 people.

There were reports Friday of demonstrations demanding Mr. Saleh's ouster in several locales across Yemen.

Mr. Saleh is recovering in Saudi Arabia from injuries sustained in a recent bomb attack on the presidential compound, as various factions, including Islamist militants, vie for power throughout the country.

The ongoing violence has prompted the United Nations to send a mission to Yemen next week to investigate human rights issues.

U.N. officials said Friday the three-member delegation would arrive in Yemen on Monday for a 10-day fact-finding mission. The delegation will meet with government authorities, rights activists, members of the opposition and alleged victims of human rights violations. The group also is planning to visit medical and detention centers.

In New York, the U.N. Security Council on Friday expressed “grave concern” about the deteriorating situation in Yemen and called on all sides to show restraint and engage in dialogue.