Pakistan's national assembly has rejected the demands of two opposition groups whose supporters have been besieging the parliament for a second day, demanding the prime minister resign over alleged election fraud.

The assembly unanimously adopted a resolution on Thursday in favour of supremacy of constitution, and the government of Prime Minister Nawaz Sharif said no unconstitutional act will be accepted at any cost.

The move comes after Pakistani officials held "initial" talks with Imran Khan, chairman of the Pakistan Tehreek-e-Insaaf (PTI), and Tahir ul-Qadri, head of Pakistan Awami Tehreek (PAT). Protests led by the two men have virtually shut down Pakistan's capital and raised fears of unrest.

Earlier, cabinet minister Ahsan Iqbal said that the two sides were trying to find a "win-win solution" even as all sides have stuck to their positions.

Thursday's talks came after Pakistan's army chief, General Rasheel Sharif, requested that Sharif's government negotiate with thousands of protesters who have surrounded the parliament.

The twin protests started last week in the eastern city of Lahore and later moved to the capital Islamabad.

The protesters tore down barricades late on Tuesday and entered the so-called "Red Zone" housing key government buildings and diplomatic posts forcing the government to deploy army in the sensitive area.

While the failed talks of senior government officials with Qadri took place inside a shipping container which the authorities had placed to block the demonstrators from marching ahead, the meeting with the representatives of Khan's party took place in a hotel close to the parliament.

Protests continue

On Thursday morning, the protesters, some carrying blankets and others colourful umbrellas, were resting outside Pakistan's parliament.

"Our demands are democratic and in accordance with [the] constitution. We will not back down a single step until they are met, even if we lose our lives," said Shehzada Aftab, supporter of Qadri, who arrived to join the protest from the city of Gujranwala in Punjab province.

The civilian government is seeking to cement its authority over the nuclear-armed nation of 180 million, after decades of oscilllating between democracy and military rule.

Most protesters on the streets of Islamabad say they are demonstrating against government corruption, which they blame for the country's widespread poverty.

Khan wants Sharif to step down because he believes the prime minister rigged last year's polls.

Sharif won the election by a landslide, taking 190 out of 342 seats in the national assembly.

The ballot was the first democratic transfer of power in Pakistan's history and also propelled Khan from a fringe player to head of the third-largest legislative bloc in the country.

Qadri, who controls a network of Islamic schools and hospitals, wants Sharif to step down because he says the system is corrupt. He has promised free housing for the homeless, and welfare and subsidised food and electricity for the poor.

Source: Al Jazeera and agencies