Japan thrashed Myanmar 10-0 on Friday to cruise into the third round of Asian World Cup qualifying, after protesters had raised anti-junta three-fingered salutes on and off the pitch.

Around 70 protesters gathered before kick-off outside the stadium in Chiba, near Tokyo, carrying pictures of detained Myanmar leader Aung San Suu Kyi and waving flags from the country's 1988 uprising.

And TV pictures showed a lone Myanmar player raising the Hunger Games-inspired three-fingered salute, commonly used by protesters.

"This team doesn't represent the Myanmar people," a protester who gave her name only as A told AFP outside the stadium before the game.

"This isn't a protest against the players. We just want them to stop cooperating with the military junta."

Five goals for Yuya Osako helped Japan clinch top spot in Group F with two games to spare, against a makeshift Myanmar side missing several regulars who boycotted the qualifiers in protest at the coup.

Goalkeeper Kyaw Zin Htet opted out of the trip and urged the players who travelled to raise the three-finger salute.

The national anthems passed off without incident, but TV cameras captured a Myanmar player wearing a pink bib making the gesture.

Myanmar manager Antoine Hey said he did not see the incident, but was aware of the protest outside the stadium.

"I don't know the motivation, what the meaning was of this gathering," he said.

"We are concentrated on football, we are concentrated on our job, our team, our players, and we are not taking any political stand."

The game was played behind closed doors but the protesters could clearly be heard inside the stadium before kick-off.

Their permission to be there ended before the game began.

One protester, who gave his name as Win, said Myanmar's side was "not a real team".

"They don't want to play, but maybe they have a lot of pressure," he said.

Japan's Takumi Minamino opened the scoring in the eighth minute, before Osako helped himself to a hat-trick before the interval.

Two more goals for Osako and strikes from Hidemasa Morita, Minamino, Daichi Kamada and Ko Itakura rounded off an easy night for the Group F hosts.

Japan has won six games from six, with 37 goals scored and none conceded.

"Whoever you play against, winning well, not conceding any goals and stopping your opponents from doing what they want to isn't easy, regardless of the difference in quality," said manager Hajime Moriyasu.

All of the remaining games in Group F are being played in Japan.

Japan round out their campaign against Tajikistan and Kyrgyzstan.

Myanmar will also face Kyrgyzstan and Tajikistan as they look to claim second place in the group.