Islamabad, Aug 5 (IANS): Three people were killed and over 15 injured Monday when a bomb went off inside a train in Pakistan, a media report said.

The blast happened at about 1 p.m. inside Shalimar Express when it reached Chatiana area of Toba Tek Singh, a district in the country's eastern Punjab province, reported Xinhua citing Geo TV.

Police said a home-made bomb packed with at least eight kg of explosive material was put inside a travel bag placed in the washroom of one of the train's compartments.

Sources said the train was owned by a private company which had been receiving threat calls from unidentified people. The owners said that the unidentified callers demanded a sum of $500,000 and upon their failure to pay it, they triggered the explosion.

Railway Minister Khawaja Saad Rafique condemned the blast and called a high-level meeting to discuss the security situation of passenger trains.

The injured have been shifted to the district hospital where at least four of them were in critical condition.