No casualty or injury to any passenger was reported. Services on Narkatiyaganj-Gorakhpur rail route were suspended after the blast.
Railway officials rushed to the site to supervise restoration works, railway sources said.
Sonepur-Gorakhpur passenger train was passing through the Chamua
The sabotage was caused to stop movement of trains during the 24-hour bandh in four states of Jharkhand, Bihar, Orissa and Chhattishgarh sponsored by proscribed CPI (Maoist) to protest arrests of four top 'commanders' of the outfit.
The Maoist rebels also blew up a government building at Jhemiri village under Semra police station of West Champaran district on Sunday night.
Official reports in Bettiah said that the building belonged to Champaran Forest division two.