Cricket great Imran Khan has declared victory for his party in Pakistan’s historic elections, promising a “new” era for the country.

Mr Khan, who aspires to be the country’s next prime minister, said in a televised address to the nation on Thursday that “thanks to God, we won and we were successful”.

He added: “If God wills, we will set an example.”

Pakistan’s election commission has not yet released official, final results but Mr Khan has maintained a commanding lead according to projections by many television stations, though it’s unclear if he will have to form a collation government.

Mr Khan’s message of a “new” Pakistan resonated with young voters in a country where 64 per cent of its 200 million people are below the age of 30, according to a United Nations report.

More than a dozen TV channels in Pakistan, based on official but partial counts, are projecting that Mr Khan’s Pakistan Tehreek-e-Insaf party will win as many as 119 seats of the 270 National Assembly seats that were contested.

However, final results have been delayed and opponents have alleged vote rigging.

Supporters of jailed ex-premier Nawaz Sharif said there were problems with the vote count and the process was an assault on democracy in a country that has a history of military rule.

“It is a sheer rigging. The way the people’s mandate has blatantly been insulted, it is intolerable,” Pakistan Muslim League-Nawaz president and Sharif’s brother Shahbaz, told a news conference as the counting continued.

Mr Khan offered to investigate all the claims of rigging and said he wants to “unite” the country under his leadership.

Election Commission secretary Babar Yaqoob said counting had been delayed by technical failures in an electronic reporting system and the tallying was now being conducted manually.

“There’s no conspiracy, nor any pressure in delay of the results. The delay is being caused because the result transmission system has collapsed,” Mr Yaqoob said.

-with AAP