YANGON (Reuters) - Aung San Suu Kyi's National League for Democracy (NLD) expects to have won only seven of 13 seats up for grabs in by-elections, a spokesman said on Sunday, conceding that Myanmar's ruling party needed to do more for voters from ethnic minorities.
The polls, held on Saturday, will not alter the balance of power but were seen as an early test ahead of a general election in 2020.
Nobel laureate Suu Kyi promised to make ending the country's decades-old ethnic conflicts her government's top priority, but peace talks have stalled and fighting has intensified.
"We lost five out of six seats in ethnic areas. Ethnic people are not satisfied with our performance on the peace process," said NLD spokesman Myo Nyunt, sharing the party's understanding of the results ahead of an official announcement by the election commission.
"This result is a lesson for us. We will come up with a strategy for each constituency for the coming election."
Suu Kyi has led Myanmar's civilian administration since winning a majority in both houses of parliament in 2015 elections that ended decades of military rule.
But she must share power with the army, which automatically takes 25 percent of parliamentary seats under a military-drafted constitution.
Saturday's polls included seats in state and regional legislatures, as well the national parliament in the capital, Naypyitaw.
The NLD won most of Saturday's contests in the central heartland where ethnic Bamar Buddhists make up the majority.
In the northern state of Kachin, the NLD finished third in an Upper House race it had won in 2015.
On Saturday, the seat in state capital Myitkyina went to the military-aligned Union Solidarity and Development Party, with several formerly separate ethnic Kachin parties throwing their support behind the Kachin Development Party (KDP), which finished second.
Gumgrawng Awng Hkam, the KDP candidate, told Reuters he was concerned that a large number of advance votes from a military cantonment in the city appeared to have swung the result in favour of his military-backed opponent.
A group of monitors led by the People's Alliance for Credible Elections said on Sunday that election authorities in Myitkyina accepted advance votes that arrived at a polling centre after a 4 p.m. cut-off time for voting. Late votes were not accepted elsewhere, they said.
"Generally, election day was smooth, and no big incidents have been reported," the monitors said in a statement.
Eleven of the seats contested on Saturday fell vacant when legislators died in office, a reflection of Myanmar's aging political leadership.
One seat, for Yangon's Tamwe township, fell vacant when the previous MP, Win Myint, became president. The NLD won the seat comfortably on Saturday.
(Reporting by Thu Thu Aung and Simon Lewis; Editing by Catherine Evans)