An explosion occurred on Wednesday night at the Polish Consulate in Lviv, Western Ukraine. No one was injured.

An explosive device had been apparently left in a bin outside the consulate and it went off at around 10:30 pm local time, according to Ukraine's interior ministry.

Spokesman for Poland's foreign ministry Marcin Wojciechowski confirmed on Twitter on Thursday morning that “an incident occurred overnight” and that “no one was hurt.”

Meanwhile, Ukraine's interior ministry said in a communique that “the reason for the explosion is being investigated.”

Poland has been among Ukraine's staunchest allies since President Viktor Yanukovych was ousted from power in February 2014.

Warsaw vehemently criticised Russia's annexation of Crimea in March 2014, and it has backed Kiev in its struggles with pro-Russian separatists in Eastern Ukraine.

Lviv is a city with considerable Polish heritage as it was a part of the Polish-Lithuanian Commonwealth before being annexed by the Habsburg Empire in 1772. When Poland re-emerged as a sovereign state following World War I, the city became part of Poland again after battles with Ukrainian forces. Polish rule ended with the Soviet invasion of 1939. (nh/rk)