Jakarta – A bomb exploded in Indonesia's volatile Ambon city as police tried to defuse it on Wednesday, wounding six people including two police officials.

Residents had found a suspicious package in a market place and called police, a police spokeswoman said.

"The bomb exploded when police tried to disarm it, hurting two of them and also four civilians," the spokeswoman said by telephone from Ambon. She said police were investigating. She gave no more details.

Ambon is 2,300 km east of Jakarta and is the key city in the Moluccas islands, scene of more than three years of Muslim-Christian violence that has killed 5,000 people.

While clashes have subsided since the warring parties signed a peace deal earlier this year, periodic violence and bomb blasts occur. Indonesia is mainly Muslim, although the Moluccas is home to roughly equal numbers of Muslims and Christians.

The Moluccas has been one of several flashpoints where separatist, communal or religious tensions pose a challenge to Jakarta's efforts to maintain order and convince investors and aid donors that Indonesia's vast archipelago is stable.