JAKARTA, Nov 19 (AFP) - Indonesian President Susilo Bambang Yudhoyono should intervene to free three Papuan protesters sentenced to years in prison for raising a separatist flag, a rights group said Thursday.

Roni Ruben Iba, Isak Iba and Piter Iba were sentenced to between two and three years in jail for subversion last week for raising a banner similar to the region's banned "Morning Star" flag, Human Rights Watch said.

The men are among scores who have been jailed on such charges in the vast region on the western end of New Guinea island, where pro-independence sentiment has run high since its incorporation into Indonesia in the 1960s.

"The prosecutions violate internationally protected rights to freedom of expression and peaceful assembly codified in the International Covenant on Civil and Political Rights, which Indonesia ratified in 2006," the group said.

"President Yudhoyono has a chance to show Papuans before the December 1 anniversary (of a Papuan independence declaration) that Indonesia is a rights-respecting country that upholds free expression," deputy Asia director for Human Rights Watch Elaine Pearson said in a statement.

"Yudhoyono should have these men freed without delay."

The group also called for Yudhoyono to drop flag-raising charges levelled against two other Papuans this month.

Indonesian courts have handed down stiff penalties from 20 years jail to life for people caught with separatist symbols such as the Papuan flag.

More than 170 people are currently imprisoned in Indonesia for peacefully promoting separatism in Indonesia, most of them from Papua or the eastern Maluku islands, according to Human Rights Watch.