(Reuters) - Candidates backed by the party of jailed Pakistani opposition leader Imran Khan plan to form a government, a senior aide to the former prime minister said on Saturday, urging supporters to peacefully protest if final election results are not released.

The nation of 241 million people voted on Thursday in a general election, as the country struggles to recover from an economic crisis and battles militant violence in a deeply polarized political environment.

Both Khan and his main rival, three-time former Prime Minister Nawaz Sharif, declared victory on Friday, increasing uncertainty over who will form the next government at a time when swift policy action is needed to address multiple challengers.

Gohar Khan, the chairman of Khan's Pakistan Tehreek-Insaf (PTI) party who also acts as the former prime minister's lawyer, called on "all institutions" in Pakistan to respect his party's mandate.

At a press conference, he said if complete results of the polls were not released by Saturday night, the party would hold peaceful protests on Sunday outside government offices returning election results around the country.

Hundreds of Khan's supporters rallied in the northwestern city of Peshawar led by two of his aides who said they had been declared losers despite having won the polls.

"We never expected it would happen to us," said Taimur Khan Jhagra, one of Khan's former provincial ministers.

The protesters chanted slogans against what they called a vote fraud.

Sharif said on Friday his party had emerged as the single largest group and would talk to other groups to form a coalition government.

By 5 p.m. (1200 GMT) on Saturday, results were still not in for 10 of the 265 seats contested in the election - 48 hours after the polls closed.

The latest tally, posted on the election commission's website, showed independent candidates had won 100 seats, with Sharif's Pakistan Muslim League-Nawaz (PML-N) taking 72 seats.

At least 90 of the victorious independent candidates were backed by Khan and his party, a Reuters analysis showed - putting them well ahead of Sharif's party.

Khan's supporters were running as independents because they had been barred from contesting the polls under his party's electoral symbol by the election commission for not complying with electoral laws.

Despite the ban and Khan's imprisonment for convictions on charges ranging from leaking state secrets to corruption to an unlawful marriage, millions of the former cricketer's supporters came out to vote for him, even though he cannot be part of any government while he remains in prison.

However, under Pakistan's electoral laws, independent candidates are not eligible to be allocated reserved seats, 70 of which are meant to be distributed according to party strength. Sharif's party could get up to 20 of these seats.

Khan's close aide and media adviser, Zulfi Bukhari, told Reuters the party would announce within the next day the party banner they will ask independents to join. In Pakistan, independent candidates cannot form a government on their own and need to join a party.

"And we have no fear of independents going anywhere, because these are the people who have struggled for the last 18 months and endured all kinds of torture and oppression," Bukhari told Reuters in a WhatsApp voice message.

Whoever seeks to form the next government would need support from other parties with no one close to the seat threshold for a simple majority in parliament.

Beside Khan and Sharif, the Pakistan Peoples Party of Bilawal Bhutto Zardari, the son of assassinated premier Benazir Bhutto, remains a major player with at least 53 seats.

The rest were won by small parties and other independents. This sets up a period of intense political negotiations over the next few days before a parliamentary vote to elect a new prime minister and government can take place.

"No one can form a government without us," Bhutto Zardari told local Geo TV.