Vowing to continue their anti-royal protest, political parties in Nepal will hold a massive rally on Thursday, which marks the start of the third week of their pro-democracy agitation.

The seven-party alliance has vowed to stage a rally on April 20 in defiance of the government's warning of a further crackdown. Hundreds of thousands of people will march towards the centre of the capital breaking any security cordon on the day, a party leader said.

Government spokesman and Communication Minister Shris Shumsher Rana has warned that government may crackdown on demonstrators by imposing emergency and some rights may be suspended if the security situation becomes untenable.

Meanwhile, armoured military vehicles escorted a convoy of trucks and buses carrying the first supplies and passengers to head for the capital as the crippling protest entered its 13th day on Tuesday. The pro-democracy agitation has crippled life in Kathmandu and other major cities around the country.

The strike has cut off fresh food and fuel supplies to the capital since April 8. No vehicles are plying on the highways and goods from Terai and India have stopped reaching Kathmandu despite government's claim to have provided security, reports said. Inflation may reach two digit mark if the current crisis continues, warn economists.

Six people have been killed, hundreds wounded and thousands jailed in the past two weeks of general strike and agitation.

Nepal's opposition leaders have called for active role by India to press the King to restore democracy. International community, including India should exert pressure on the King to immediately restore democracy and civil rights in Nepal, said Sekhar Koirala, Nepali Congress central member and nephew of party president Girija Prasad Koirala.

"International community can put smart sanctions against top officials of the Royal government and those security personnel who have role in cracking down on demonstrators," he said. Stopping visa to high government officials and ceasing their property in foreign bank are some of the options international community can take up under the smart sanctions, he said.

Civil servants and bank employees have also joined the movement to restore democracy, saying without democracy their rights cannot be guaranteed. The country's 80,000 civil servants will join the movement to restore democracy, said Bhanubhakta Dhakal, former president of Nepal Civil Servants Association. Bank transactions have halted since Monday after private bank employees joined the movement.