By Ognjen Teofilovski
KUMANOVO, Macedonia, May 10 (Reuters) - Sporadic gunfire could be heard in an ethnic Albanian suburb of northern Macedonia on Sunday, after a day-long gun battle between police and an 'armed group' killed six policemen and wounded about 30.
The Interior Ministry said a sixth policeman had died overnight in hospital. It said an unspecified number of gunmen were killed but gave no information on civilian casualties during the clashes that began in the town of Kumanovo, 40 km (25 miles) north of the capital Skopje, early on Saturday.
The government proclaimed two days of national mourning.
A Reuters photographer said Kumanovo was tense but relatively calm on Sunday, with sporadic gunfire.
A police source said police were "still trying to break the remaining elements of the terrorist group".
Police said on Saturday they had acted on information about an "armed group" and launched an operation in an ethnic Albanian district of Kumanovo, in a region that saw heavy fighting during an ethnic Albanian insurgency in 2001.
Units of special police in armoured vehicles locked down the neighbourhood and helicopters circled overhead. A Reuters photographer reported hearing heavy automatic gunfire and loud explosions. Black smoke rose over the town and residents were seen leaving the area carrying belongings.
The events will deepen concern in the West over stability in Macedonia, where the government is on the ropes over allegations by the main opposition, the Social Democrats, of illegal wire-tapping and widespread abuse of office.
Protesters demanding the resignation of conservative Prime Minister Nikola Gruevski clashed with police this week and the opposition is threatening to rally thousands on May 17.
Observers fear political leaders on either side may try to stoke ethnic tensions as leverage.
An Interior Ministry spokesman said on Saturday the group in Kumanovo was planning "terrorist acts" and had "infiltrated" the country from a neighbouring state, without saying which.
Macedonia's neighbours are Albania, Greece, Kosovo, Serbia and Bulgaria. Macedonia has previously identified armed men in the country as coming from Kosovo.
An estimated 30 percent of Macedonia's 2 million people are ethnic Albanians. Guerrillas took up arms in 2001, clashing with security forces before the West brokered a peace deal offering the Albanian minority greater rights and representation and the insurgents entered government.
But implementation has been slow and tensions sometimes flare. Many citizens, regardless of ethnicity, are frustrated at the slow pace of development and integration with the West. Macedonia's bid to join the European Union and NATO is blocked by a long-running dispute with Greece over the country's name. (Additional reporting by Kole Casule in Skopje; Writing by Zoran Radosavljevic; Editing by Janet Lawrence)