Aung San Suu Kyi's opposition called for calm Friday after a party MP was wounded by a sword-wielding attacker while canvassing in Yangon, as tensions rise in the days ahead of key elections in Myanmar.

Naing Ngan Linn, a sitting MP for the National League for Democracy, suffered injuries to his head and arms when he was set upon late Thursday as his campaign group toured Tharketa township in his constituency.

In a statement on the bloody assault, the NLD urged its members to engage their campaigns with "continued momentum" as the party gears up to contest nationwide elections for the first time in a quarter of a century on November 8.

"We call on all NLD members around the country not to respond in any way to the violence in Tharketa to ensure that the coming elections pass peacefully," the party's election committee said in the release.

Naing Ngan Linn and another party member continued to receive treatment late Friday at Yangon General Hospital, where they were earlier visited by Suu Kyi and other party officials, who have called the assault the worst incident of the campaign.

Political tensions are high in former junta-run Myanmar with the opposition likely to make major gains in the vote, potentially tipping the balance of power away from the military and its ruling party allies for the first time in generations.

Witnesses earlier described a terrifying attack on the NLD group by a man who appeared drunk and charged at the canvassers, brandishing a sword.

"Naing Ngan Linn tried to stop him... that's why he sustained many injuries," said Thet Htar Nwe Win, another NLD candidate, who was present during the incident.

He added that several other unarmed men had attacked the group but it was not clear what motivated the violence.

Thet Htar New Win said at least two people had been arrested.

Khin Sandar Win, the injured MP's wife, said he suffered wounds on his forehead, hands and wrists and had undergone an operation on Thursday. His condition was not life threatening.

"It happened in front of my eyes. The man who attacked was shouting abusive words against NLD when our vehicle arrived," she told AFP.

Myanmar's elections are set to crown more than four years of reforms that have seen the nation open its doors to the world under a quasi-civilian regime that replaced junta rule in 2011.

Campaigning has largely been calm, although the NLD has complained that its rivals have used religion as a political tool.

Those concerns carry weight in a nation that has seen waves of anti-Muslim violence in recent years.

The attack comes just days before Suu Kyi is due to speak at a major rally in Yangon at the culmination of weeks of energetic campaigning around the country by the veteran activist.

A spokesman for the party who was overseeing preparations at the rally site Friday said there would be "normal" security for Sunday's event.