(CNN) -- Tens of thousands of anti-government protesters are expected to join a march on Pakistan's capital as the country celebrates its independence.
The protest was called by former Pakistan cricket captain and leader of the Tehreek-e-insaaf (PTI) political party, Imran Khan, who declared it a "march of independence." He has demanded the resignation of Prime Minister Nawaz Sharif amid claims of vote rigging during last year's election.
Another prominent opponent of the government, outspoken cleric Tahir ul Qadri, also called on his supporters to join what he described as a "revolution march," sparking fresh security fears. Last week, at least five of his supporters were killed during clashes with security forces in the country's northwestern Punjab province. Qadri, who led protests against Pakistan's government last year that brought the capital to a standstill, has accused the Sharif government of corruption.
Qadri has previously called for the military to be involved in the electoral process, causing alarm in a country with a history of coups. Critics accuse the cleric, who was until recently based in Canada, of working on behalf of the military -- an allegation he denies. He maintains that he is working only to ensure a corruption-free electoral process.
Thousands of security personnel have been deployed along the planned route from the city of Lahore to Islamabad, while massive shipping containers and reels of barbed wire have been used to seal off many roads. Cell phone coverage has also been temporarily suspended across some areas. Under Section 144 of Pakistan's penal code, the authorities have prohibited "all kinds of gatherings of five or more persons, processions/rallies and demonstrations at any public place," while control of Islamabad's security has been handed to the army.
Representatives of opposition leader Khan told CNN that they planned to arrive in the capital at 6 p.m. local time (9 a.m. ET) on Thursday, where they will rally in the city's "red zone," a tightly controlled area containing many government buildings. Pakistan's Dawn News reported that an agreement has been struck between authorities and protest organizers to permit the rally on the condition participants remain in Islamabad for one day only. CNN could not confirm this.
On Wednesday, in a rare address to the country, Prime Minister Sharif refuted accusations of electoral rigging and stressed that Pakistan has moved forward over the past 14 months in terms of "currency value, foreign investment and economic growth." In an apparent attempt to appease Khan's demands for an investigation into electoral fraud last year, Sharif offered to form a commission consisting of three Supreme Court judges to investigate the claims.
But at a press conference shortly after the prime minister's address, Khan said the government's response had arrived too late in the day and that he was now officially calling for the resignation of Sharif.
Protest leaders are expecting around 100,000 people to join the march during what is a national holiday to mark Pakistan's independence following British rule in 1947.
Pakistan, so often a nation in crisis, is currently involved in a costly military campaign against militants in its restive northwestern tribal region. But the air and ground offensive has displaced an estimated 500,000 people -- including 180,000 children according to the United Nations -- from their homes in North Waziristan.