The national election is the first since Sogavare struck a security pact with China in 2022, inviting Chinese police into the archipelago and drawing the Pacific Islands nation closer to Beijing.
The election is being watched by Australia, China and the United States because of the potential impact on regional security.
Electoral officials in Honiara are counting ballots after the Solomon Islands elections. (Mick Tsikas/AAP PHOTOS)
Sogavare's police minister, Anthony Veke, lost his seat of West Guadalcanal to the biggest opposition party, Solomon Islands Democratic Party (SIDP), local broadcaster SIBC reported on Tuesday.
With two seats still to be announced, the CARE coalition of Matthew Wale's SIDP, U4C and former prime minister Rick Hou's Democratic Alliance Party (DAP) was on 13 seats, while Sogavare's OUR party also had 13 seats in a 50-seat parliament.
Another prominent opposition party, Peter Kenilorea Jr's United, which said it would scrap the China security pact, won seven seats.
United is likely to join CARE, boosting it to 20 seats, a source with direct knowledge told Reuters.
Kenilorea told Reuters "we have not joined CARE at this time".
Independents and micro parties hold 15 seats, and Sogavare's OUR party and CARE will both seek to win independent support in the race to find the 26 seats needed to form government.
Negotiations in the capital Honiara begin as newly elected MPs arrive from other islands.
Independents will be key to forming government as newly elected MPs arrive in Honiara for talks. (Luke Costin/AAP PHOTOS)
Past elections have shown coalitions can be fluid.
"The next several days will see a lot of horse trading given that no party has won an absolute majority," DAP leader Hou said.
"It's hard to ascertain any outcome - it's too fluid."
Election officials said three women had won seats, and there had been an 80 per cent turnout of voters.
Police and defence forces from Australia, New Zealand, Papua New Guinea and Fiji are assisting with election security.
The Royal Solomon Islands Police Force Commissioner Mostyn Mangau said in a statement the police force was "a neutral law enforcement organisation which is not politically affiliated" after he said some people had expressed distrust in security over the election counting process.
