Ex-army general Prabowo Subianto has controversially claimed victory in Indonesia’s presidential election, despite unofficial results from more than half a dozen credible pollsters indicating that incumbent Joko Widodo has comfortably won.

Speaking to supporters and journalists gathered outside his residence in South Jakarta on Wednesday evening, hours after the polls had closed, the fiery former special forces commander delivered a triumphant speech.

“My fellow countrymen, this is a victory for the Indonesian people. All of the Indonesian people and I tell you here, that I will be the president for all Indonesians,” he said. “I will be and I already am the president of all Indonesians.”

Prabowo, the former son-in-law of Indonesia’s longtime autocratic ruler Suharto, claimed that based on a real count conducted by his team, early indications showed him in the lead with 62%.

Earlier on Wednesday his team said an internal exit poll showed Prabowo had defeated the incumbent president, known as Jokowi, garnering 55.4% of the vote.

The proclamations run counter to more than half a dozen quick counts conducted by credible Indonesian survey institutes, which show Jokowi and his running mate, Islamic cleric Ma’ruf Amin took the lead by at least 9 percentage points.

Litbang Kompas, for example, found that Jokowi-Amin defeated Prabowo and Sandiaga Uno by 54.52% to 45.48, with a sample size of more than 95%.

Quick counts are based on samples of real votes and have proved reliable indicators of past results. The official tally from Indonesia’s election commission is not expected to be released until May.

Noticeably absent from Prabowo’s declaration was his running mate Sandiaga Uno, 49, a former private equities manager, who analysts believe is eyeing a 2024 presidential bid.

A member of the Prabowo team explained the absence by saying Sandiaga was not feeling well, and had a persistent bout of the hiccups.

This is not the first time Prabowo has claimed himself the rightful winner of the presidency. In the nerve-racking 2014 presidential election, which he lost to Jokowi by six percentage points, he issued similarly triumphant declarations.

An appeal subsequently lodged at the constitutional court, in which he alleged widespread electoral fraud, was dismissed.

Maintaining the electoral roll is deeply fraught with the alleged inclusion of millions of ghost voters, and it is possible the Prabowo camp will lodge another legal challenge. In a rare interview Prabowo told the Guardian last week that “if the powers that be want to cheat massively, they will be going against the will of the people”.

Addressing reporters after Wednesday’s mammoth election in the world’s third-largest democracy, Jokowi urged the public to wait for the official announcement and called for Indonesians to come together.

“Let us reunite as brothers and sisters of the country after this election, establish our harmony and brotherhood,” he said.

Indonesia’s election commission (KPU) has also warned both candidates to maintain public order and refrain from claiming victory before the official results are released.