Uganda's electoral commission on Thursday night assured that transmission of election results to the national tally centre is ongoing despite a nationwide internet shutdown in the country.

The commission's head, Simon Byabakama, said they are using an internal mechanism to transmit the results, but did not offer details.

"We're not using local internet to transmit results. We are using our own system. Don't worry, the results will come in spite of the fact that internet has been shut down," he told journalists.

It released preliminary results early Friday from 330 polling stations that gave incumbent President Yoweri Kaguta Museveni an early lead, the Daily Monitor newspaper reports.

The country has a total of 34,684 polling stations.

Ugandan law provides for the electoral commission to ascertain results received from all the districts and declare them within 48 hours after closing of polls.

Winners of parliamentary seats will be declared at district tally centres, while the winner of the presidential election will be declared at the national tally centre in the capital, Kampala.

Robert Kyagulanyi, known by his stage name Bobi Wine, has emerged as the strongest challenger against President Museveni.

Earlier in the week the authorities ordered the blocking of social media, messaging apps and certain sites for virtual private networks (VPNs) which people use to get around social media blocks.