A series of attacks in conflict-hit northern Myanmar left at least four officials dead, state media said Sunday, in rare acknowledgement of ethnic unrest that has marred the regime's reformist image.

Rebels were said to have launched a deadly assault on a government office in Waingmaw Township, Kachin State, where heavy fighting has raged for a year despite the new quasi-civilian government's insistence that it wants to reach peace deals with the country's various armed rebel groups.

"So, measures should be taken to avoid another incident... Such a terrorist attack is totally unacceptable in the time of peace efforts," said a report in the state mouthpiece New Light of Myanmar.

It said three other officials were missing following the attack.

Tens of thousands of people have been displaced by clashes between government troops and guerrillas with the Kachin Independence Army (KIA), which controls swathes of the state, since a 17-year ceasefire was shattered last year.

Conflict re-erupted in June as anger grew over a clutch of Chinese-backed hydropower projects in the region and fighting has raged since then.

State media on Sunday also reported a separate incident involving heavy weapons fire in another area, where 200 KIA fighters were said to have captured vehicles belonging to a Myanmar construction giant linked to a Chinese company working at one of the dam sites.

The army was "in hot pursuit", the report added.

Civil war has gripped parts of Myanmar since independence in 1948. An end to the conflicts and alleged rights abuses involving government troops is a key demand of the international community.

Media coverage of the unrest comes amid several high-level visits to Myanmar, including UN leader Ban Ki-moon and top European Union diplomat Catherine Ashton.