( dpa ) - A series of bombs exploded at a political rally in restive southern Nepal Sunday injuring at least 13 people.
About a dozen bombs exploded in and around the venue of a mass gathering organized by Prime Minister Girija Prasad Koirala's Nepali Congress Party in the town of Rajbiraj, about 450 kilometres east of the Nepalese capital Kathmandu.
"The bombs went off at an interval of every ten minutes around the venue in an attempt to disrupt the mass gathering," Deputy Superintendent of Police Bikram Singh Thapa said. "One bomb went off within 100 metres from the leaders addressing the gathering."
Among those injured included two policemen. The condition of four of the injured is reported to be serious.
The gathering went ahead despite the blasts.
"We have detained seven people suspected of involvement in the blasts," Thapa said.
No there were immediate claims of responsibility.
Armed ethnic Madhesi groups have previously carried out similar attacks on political gatherings in southern Nepal in recent days.
The rally was an attempt by the Nepali Congress party to spread awareness about key elections scheduled for April 10 to choose a constituent assembly to rewrite the country's constitution and ratify a decision of the parliament to abolish monarchy.
Ethnic Madhesi groups say they are opposed to the elections until there are guarantees of more seats for the ethnic group and fulfilment of other demands, including declaration of southern Nepal as an autonomous area.
Earlier in the week, at least 50 people were injured when two bombs went off outside the venue of a mass gathering in Birgunj organized by the seven party alliance.
Southern Nepal has seen some of the worst violence since Maoists rebels signed a peace deal with the government to end a decade long communist insurgency in November 2006.
Violence in southern Nepal since then has claimed the lives of more than 130 people.