Transparency International in Solomon Islands says there was widespread treating prior to the election early this month and this was a factor in the riots last week.
Its chairman, Paul Roughan, says while the election was deemed by monitors to have been free and fair, there were significant issues which helped provoke the violence.
The rioting began after the announcement of Snyder Rini as Prime Minister.
He has since resigned.
Mr Roughan says while the election itself was not marred by the brandishing of weapons or the theft of ballot boxes, there were still significant concerns.
"It's not widely perceived outside of the Solomon Islands, but there are considerable concerns in certain constituencies - about treating, significant treating before the election. Observations on election day only catch a little of the whole story. So an awful of the people who got back - you will probably hear of some petitions and officials complaints being lodged about their conduct."