Mobile phone footage captured the moment of the explosion, which turned the night's sky orange and was so powerful it could be heard as far away as downtown Donetsk, almost four miles away.

The blast came as diplomats predicted that Russia could target other Baltic states, if they are allowed to hold on to eastern Ukraine. 

Last night, locals posting on social media speculated it was could have been caused by a nuclear weapon due to the ferocity of the shelling and the impact on the chemical plant.

It also temporarily caused a mushroom cloud to hang over the city with the bombing shattering windows and shaking building foundations.

However, pro-Russian rebels said that the huge explosion was caused by Ukrainian artillery shell hitting the chemical plant, which lies in the middle of the Ukrainian industrial heartland in Donetsk.

It has long been feared that shelling would hit industrial units causing a huge explosion such as this.

Luckily, no damage or injuries were caused in the blast but the conflict between Russia-backed separatists and government forces has now killed more than 5,300 people and displaced more than a million.

Fighting between pro-Russian rebels and pro-government forces loyal to Kiev has intensified in Ukraine's south east region since the new year, even though the two sides agreed a truce in September. 

And now diplomats are warning that Russia could be planning to target other Baltic states with Estonian president Toomas Hendrik Ilves comparing appeasing president Vladimir Putin to that of when Nazi Germany was allowed to seize parts of the former Czechoslovakia in 1938.

He said he had no fears about a Russian invasion of his country but accepted the security environment in the Baltic area had 'dramatically changed'.

(dailymail.co.uk)