Clashes broke out Friday as protesters led in convoys by cricketer-turned-politician Imran Khan and a populist cleric advanced on the Pakistani capital to try to topple the government they say was elected by fraud.

Khan and preacher Tahir-ul-Qadri say the May 2013 general election that brought Prime Minister Nawaz Sharif to power in a landslide was rigged, and are demanding he resign and hold new polls.

Thousands of protesters on Thursday began a march from the Pakistani city of Lahore to the capital in a bid to unseat the government, which they claim was elected by fraud.

Supporters of cricketer-turned-politician Imran Khan and populist preacher Tahir-ul-Qadri massed separately in Lahore before announcing the start of their 300-kilometer (190-mile) journey to rally in Islamabad.

A populist Canada-based cleric returned to Pakistan on Monday to try to start what he has called a "peaceful revolution" against the government, as his supporters engaged in violent clashes with police.

Tahir-ul-Qadri touched down in the eastern city of Lahore after his flight was diverted from Islamabad following violence at the capital's airport that police said left more than 70 of their officers injured.

Three separate bomb attacks -- two in the capital Islamabad and one in a restive tribal region -- killed six soldiers and one civilian in Pakistan on Saturday, officials said.

The explosions followed three days of intensive Pakistani military airstrikes against Taliban hideouts near the Afghan border, which killed at least 75 people.

Thousands of opposition supporters held a rally in the Pakistani capital Islamabad on Sunday protesting against alleged rigging in last year's general election, amid simmering tensions between the government and army.

The demonstration was led by cricketer-turned politician Imran Khan as well as charismatic preacher Tahir ul Qadri, who held an anti-corruption march last year prior to the May 2013 election that saw the country's first democratic handover of power.

A bomb tore through a bustling fruit and vegetable market in Islamabad Wednesday, killing at least 22 people, police said, the latest violence to hit government peace talks with the Taliban.

The blast took place around 8:00 am (0300 GMT) at the wholesale market close to the Pakistani capital's twin city Rawalpindi, as hundreds of grocers and sellers gathered to trade.

Pakistan on Monday said it was "highly disturbing" to see attempts being made to implicate it in an attack on a Kabul hotel that left nine civilians dead, including an Agence France Presse journalist.

Afghanistan said on Sunday that the attack on Kabul's Hotel Serena was planned "outside the country," in a veiled reference to Pakistan.

Afghanistan on Sunday said an attack on a Kabul hotel that left nine civilians dead, including an Agence France Presse journalist, was planned "outside the country" in a veiled reference to Pakistan.

The National Security Council (NSC), which is chaired by President Hamid Karzai, also alleged that a Pakistani diplomat was seen scoping out the corridors of the Serena hotel ahead of the Thursday night raid.

At least 10 people including two children and as many women were killed when a bus fell down a hill just northeast of Pakistan's capital Islamabad, officials said on Sunday.

The bus, which was carrying 20 passengers from the hill town of Murree to Rawalpindi, lost traction on a slippery road amid rainfall, rolling on its side as it fell down a slope.

Two separate bomb attacks targeting security forces in Pakistan killed 19 people on Friday, officials said, the latest violence to hit peace talks between the government and Taliban militants.

A suicide attack in the suburbs of the northwestern city of Peshawar, close to the lawless tribal areas that are a haven for Taliban and Al-Qaida linked militants, was followed a few hours later by a bombing in the southwestern city of Quetta.