Clashes have flared between Myanmar's army and rebels in an ethnic Chinese northern border area, state media said Tuesday, as multiple conflicts in minority regions overshadow efforts to agree a countrywide ceasefire.

Resurgence of conflict in the Kokang area of Shan state, which had been largely dormant for nearly six years, saw rebel troops attack Myanmar military positions in the area on Monday.

"While the State is making all-out efforts for reaching a nation-wide ceasefire, the renegade groups of Kokang have ambushed the troops of the Tatmadaw (army)," said a report in the English language Global New Light of Myanmar.

It said the clashes in the predominantly ethnic Chinese area of Kokang had stoked "worries" among local people that there would be "recurring fighting there".

The fighting comes as conflict between the military and armed ethnic minority groups rages in other parts of Shan and northern Kachin states, casting doubts over government efforts to ink a nationwide ceasefire deal.

Myanmar had hoped to sign the long-delayed agreement on Thursday, as the country celebrates its annual Union Day celebrations.

But officials said a full deal was not yet on the table.

"We will not be able to sign the Nationwide Ceasefire Accord because there are some negotiation points still left to discuss," Hla Maung Shwe, a negotiator with the Myanmar Peace Centre, told AFP.

Myanmar's government, which replaced junta rule in 2011, has vowed to end the civil wars that have been flaring on and off since independence as a key part of its reforms.

Conflict between the government and Kachin Independence Army (KIA) has festered since a 17-year ceasefire between rebels and the government collapsed in 2011, driving almost 100,000 civilians from their homes.

Fighting has increasingly spread to northern Shan state, where last week the Ta'ang National Liberation Army (TNLA) accused Myanmar's army of using two helicopter gunships against its positions in another part of Shan state.

In 2009 more than 30,000 people flooded over the border into China as Myanmar's army launched an offensive against Kokang rebels.

The fighting earned Myanmar's then junta government a rare rebuke from Beijing, the country's powerful northern neighbour which at the time was almost its sole ally on the international stage.

On Monday Xinhua reported that hundreds of Kokang rebels had launched assaults on four areas that afternoon.

The United Nations local representative on Thursday raised concerns about violence last month around Kachin's Hpakant township, a jade-rich area near the border with China, which trapped hundreds of civilians.