Kathmandu, Jun 14: A bomb has exploded at the office of a major hydropower project being constructed with Indian assistance in Nepal, the second such incident at the facility in over a month.

An unidentified group exploded an improvised explosive device in the office of Arun III hydropower in Tumlingtar, nearly 500 km from here, yesterday. The explosion did not cause any serious damage and no one was injured in the incident, according to the police.

Security arrangements have been intensified following the incident, he said.

No group has so far claimed responsibility for the blast. On April 29, a CPN Maoist faction had exploded a bomb at the office of the project weeks before its inauguration by Prime Minister Narendra Modi.

A Project Development Agreement (PDA) for Arun III was signed with India's state-owned Satluj Jal Vidyut Nigam (SJVN) on November 25, 2014, in the presence of the then Prime Minister Sushil Koirala and visiting Indian Prime Minister Modi.