Maoist insurgents blew up a bus in central Nepal killing at least eight people, including six security personnel, media reports said Saturday.

The incident Friday evening - coming less than a week after a land mine planted by Maoists killed 42 bus passengers in the country - took place in Kavre district when the bus travelling through Narke village hit a landmine, the Kathmandu Post daily reported.

Two civilians were among those killed while an army man and two other civilians were injured. The injured were airlifted to Kathmandu for treatment, the Post said, quoting unnamed sources in the Royal Nepalese Army.

However, the Post report could not be confirmed by the army immediately, Saturday being a government holiday.

Maoists had detonated a powerful mine in southern Nepal Monday killing 42 bus passengers, causing the largest civilian casualty in the nine years of the communist insurgency.

The attack was widely condemned with the Indian government, UN Secretary General Kofi Annan, rights watchdog Amnesty International, several other rights groups and Nepal's political parties joining the protestors.

Nepal's top rights body, the National Human Rights Commission, and a UN agency that has recently opened an office in Nepal to monitor rights violations, the Office of the UN High Commission for Human Rights, announced they were investigating the blast.

The furore forced the Maoist leadership to issue an apology from underground, admitting it was a "grave error" and saying they would punish those involved in the incident.

In a statement issued from hiding, Prachanda aka Pushpa Kamal Dahal, the supreme commander of the communist guerrillas, pledged his banned organisation would ensure there were no civilian casualties in future.