Kathmandu, Aug 7 - After warning the government that the new constitution may not be implemented in time, Nepal's Maoist chief Pushpa Kamal Dahal Prachanda is now going on a trip to Britain even as his party triggered fresh unrest in the fragile nascent republic Friday.

This is the former prime minister's first visit abroad after his government collapsed in May.

Like his first visit abroad after assuming office, his first trip out of power is equally controversial.

The Maoist chief is leaving for London on a 10-day visit Saturday at a critical time when Nepal's peace process has been brought to a halt by his own party and the future of the new constitution lies in jeopardy.

Talking to the media in Pokhara town Friday, the former guerrilla leader warned the new communist government that the new constitution is unlikely to be promulgated by May 2010 if the rift between his party and the coalition continues to widen.

From Friday, the Maoists have called for countrywide disruptions as well as a blockade of parliament after their month-long ultimatum given to Prime Minister Madhav Kumar Nepal ended Thursday.