A gunman opened fire on a container truck carrying Pakistan’s former prime minister Imran Khan, hurting him and some of his supporters, a senior leader from his party and police said.

Mr Khan was hit in the leg but escaped serious harm, party official Asad Umar said.

The identity of the gunman was not immediately known and no group claimed responsibility for the attack.

An arrest was made at the scene.

The attack happened in the Wazirabad district in the eastern Punjab province, where Mr Khan was travelling in a large convoy of trucks and cars heading towards the capital Islamabad as part of his campaign aimed at forcing the government to hold early elections, police said.

The shooting underscored the growing political instability in Pakistan, with both the government and Mr Khan refusing to back down from their positions.

The country’s powerful military said although Mr Khan had a democratic right to hold a rally in Islamabad, no one will be allowed to destabilise the country.

Authorities in Islamabad had already deployed additional security around the city to deter any clashes or violence.

The motives of the attacker were unknown and it was unclear whether the shooting was an attempt on Mr Khan’s life.

A video posted to Twitter by journalist Wajahat Kazmi appears to show the convoy moving slowly down a busy street before several shots are fired.

Mr Khan with later seen with a bandage on his right leg, just above the foot, according to reports and a blurry image.

He was moved to another vehicle from his container truck, from which announcements were made that he is safe.

“He is being taken to a hospital in Lahore but he is not seriously wounded. A bullet hit him in the leg,” Mr Umar told reporters.

According to the Interior Ministry, the government has ordered an investigation.

A number of supporters from Mr Khan’s Tehreek-e-Insaf party were also hurt, according to the announcement from the party.

The attack happened less than a week after Mr Khan began his march from Lahore, the capital of Punjab province, along with thousands of supporters.

Since his ousting in a no-confidence vote in Parliament in April, Mr Khan has alleged it was a conspiracy engineered by his successor, Prime Minister Shahbaz Sharif, and the United States — claims both the new premier and Washington have denied.

Mr Sharif’s government said there will be no early vote and the next election will be held in 2023, according to schedule.

Mr Khan’s latest challenge to the government comes after Pakistan’s elections commission disqualified him from holding public office for five years for allegedly selling state gifts unlawfully and concealing assets as premier.

Mr Khan, who has challenged the disqualification in a pending court case, said he would sue chief election commissioner Sikandara Raja, who was behind the decision, for calling him a “dishonest person”.

It was also not immediately known if Mr Khan’s convoy will proceed on to Islamabad.

Earlier, Fawad Chaudhry, a senior leader in Mr Khan’s party, said they planned to enter Islamabad on Friday.

The attack also comes at a time when impoverished Pakistan is grappling with the aftermath of unprecedented floods that struck this Islamic nation over the summer, killing 1,735 people and displacing 33 million.