An investigation of complaints arising from the Senate election will not delay the time frame for announing the results, Election Commission chairman Ittiporn Boonpracong said.
He made the remarks after Sunday's provincial-level Senate election. The EC received a total of 80 complaints about irregularies and collusion at both the district and provincial levels as of Sunday.
Mr Ittiporn said complaints can be filed with the EC or the Supreme Court within three days of election day.
Of the 80 complaints, 78 were filed by candidates at the district-level Senate election and the others stemmed from the provincial-level election.
Most of the 78 complaints concern election law violations with some candidates accused of being hired to take part in the poll, Mr Ittiporn said.
He said the final results of the Senate election will be announced on July 2 as scheduled.
''No factors can delay the announcement of the result. We will try to ensure an investigation of complaints will be finished quickly. We will ensure justice for all candidates," the EC chairman said.
A total of 23,645 candidates who passed the district-level selection process on June 9 took part in Sunday's provincial-level vote in 77 provinces.
After Sunday's vote, a total of 3,080 applicants will now be shortlisted to vie for 200 seats at the national level on June 26 at Muang Thong Thani in Nonthaburi. The election results will be announced on July 2.
Several high-profile candidates failed to pass the provincial-level election.
They include Santhana Prayoonrat, a former Special Branch officer and a candidate for the Bangkok Senate election, who raised suspicions that collusion could be at play in the Senate election.
He said he will wait for the EC to announce the poll results before lodging a complaint with the poll agency.
Other candidates who could not make it through to the national-level election include a former election commissioner, Somchai Srisuthiyakorn, and Sonthiya Sawasdee, a former adviser to the House committe on law, justice and human rights.
According to the 2017 constitution, the new Senate to succeed the junta-appointed chamber will comprise 200 members selected from 20 professional groups, with 10 seats available for each group. They will not be directly elected by the public.
The election, organised by the Election Commission (EC), is a three-phase process in which candidates choose among themselves both from their own group and other professional groups at the district, provincial and national levels.
At the district level, there was an intra-group election in which five candidates with the highest number of votes in each group proceeded to an inter-group election. In the inter-group poll, the three candidates with the highest number of votes were shortlisted per group, or 60 across 20 groups.
The shortlisted candidates repeated a similar process at the provincial level Sunday, but this time during the inter-group poll, only the two candidates with the most votes in each group progress to the final, national stage in which the top 10 from each of the 20 groups are selected as senators.
Caretaker senator Somchai Swangkarn previously claimed provincial-level voting in the Senate election would show that several individuals were hired to take part in the process, simply to vote for candidates backed by certain parties or interest groups.
Mr Somchai claimed there are concerted attempts to manipulate the outcome of the Senate election.