“They were testing tear gas inside the practise grounds of their embassy. Gas came out onto the road in front of the embassy and some people smelled it and informed us,” he said.

No one was injured and the gas did not cause any damage to the embassy, he said.

The embassy had apologised for not informing police of the test in advance, he added.

While bombings were relatively common under the former junta that stepped down in 2011, such incidents have been rare in recent years.

A series of small blasts rocked the country in October 2013 after they appeared to target tourist spots just as the emergent nation was experiencing a flood of foreign visitors following the end of military rule.