The death toll from an explosion at a government-run coal-fired power plant in northern India has risen to 29, local officials have confirmed, as more people died from their injuries. 

"Twenty-nine persons have succumbed to injuries and 85 are being treated at hospitals," an official from the plant said.

The blast took place on Wednesday evening when a boiler pipe burst at a plant run by India's largest state-owned power utility, National Thermal Power Corporation (NTPC), in northern Uttar Pradesh state. 

Nearly 200 people were on duty when the incident happened and some are believed to be trapped under the debris as a search operation continues.

Following the incident, Rahul Gandhi, Vice President of the Indian National Congress, visited families of the victims on Thursday and expressed his shock at the "terrible tragedy".

Indian Prime Minister Narendra Modi on Thursday also expressed condolences and approved pensions for those affected by the blast, adding that the situation "is being closely monitored".

The plant, which employs around 870 people and supplies electricity to nine neighboring states, has been shut down. 

According to local media, NTPC has launched an investigation into the caused of the explosion.