GENEVA (Reuters) - International mediator Kofi Annan told Syrian President Bashar al-Assad on Tuesday that "bold steps" were required for his six-point peace plan to succeed, including a halt to violence and release of people arrested in the uprising, a statement said.

"Joint Special Envoy Kofi Annan met President Bashar al-Assad this morning to convey the grave concern of the international community about the violence in Syria, including in particular the recent events in Houla.

"He conveyed in frank terms his view to President Assad that the six-point plan cannot succeed without bold steps to stop the violence and release detainees, and stressed the importance of full implementation of the plan," said the statement issued by his spokesman Ahmad Fawzi after talks in Damascus.

Earlier, the U.N. human rights office said that fewer than 20 of the 108 people confirmed as having been killed in a massacre in Houla died from artillery and tank fire, with most of the rest shot in their homes.

(Reporting by Stephanie Nebehay; Editing by Janet Lawrence)