An official prepares ballot boxes and other voting materials in Jakarta ahead of presidential and legislative elections.
CNN  — 

Indonesia’s election watchdog is investigating possible vote-rigging before next week’s presidential and legislative elections following the emergence of video which purportedly shows tens of thousands of pre-marked ballot papers.

The video seemingly shows a raid on an empty shop in neighboring Malaysia, which resulted in the retrieval of the ballots marked for President Joko Widodo, his running mate Ma’ruf Amin and a candidate for the allied Partai Nasional Demokrat, known colloquially as NasDem.

In the video, a voice is heard saying: “Many ballots that have been punched have been collected in an unoccupied house-shop. We found directly that the president’s (name) has been punched. No. 01.

“The MP candidate no. 5 (is from) Nasdem. The name is Ahmad. Yes. This is Ahmad.”

A supporter of Indonesian incumbent Presidential candidate Joko Widodo attends a campaign rally at the Sriwedari stadium in Solo, Central Java on April 9.

The Indonesian Elections Supervisory Agency (Bawaslu) has confirmed the authenticity of the video and announced at a press conference that a team would leave for Malaysia Friday to investigate further, including determining who produced the video.

The head of election monitoring for overseas votes in the Malaysian capital Kuala Lumpur, Yazza Azzahara, told journalists at a press conference Thursday that on learning of the alleged stuffed ballots, he and another monitor rushed to the location.

“When we arrived, the condition of the place, the doors are already open, after that we went in and we found it full of ballot papers, they were in envelopes and inside bags.”

The president’s campaign has denied any involvement with the alleged ballot-rigging. “Investigations were carried out, both by Bawaslu and by the police,” Joko said at a campaign stop, according to local media.

“If there were violations, Bawaslu could take action, if there was criminality, the police must take legal action. In order for this to be an honest election it has to be fair,” he said.

CNN has reached out to the president’s office for further comment.

Indonesia's general elections will be held on April 17 pitting incumbent President Joko Widodo against Prabowo, who he defeated in the last election in 2014.

The country goes to the polls on April 17, with Joko, who is commonly known as Jokowi, seeking re-election against a challenge from former general Prabowo Subianto.

Prabowo’s campaign sharply criticized the revelations, saying that they amounted to “a blatant show of thievery in Indonesian presidential election.”

Prabowo’s campaign director, Sugiono, said that the opposition found it “ridiculous, disturbing and undemocratic. People in Indonesia want change and they have been showing their support to Prabowo.

“The only way they can win this election is by stealing it like what they were doing in Malaysia. Is there any guarantee that this will not happen anywhere else?”

Many Indonesians who live or work overseas can vote in their countries of residence. But voters based in Malaysia are not due to cast their ballots until Sunday.

There are almost 200 million registered voters in Indonesia, with over 811,000 polling stations including 783 overseas polling stations in 130 countries, according to the International Foundation for Electoral Systems, a non-profit which monitors elections worldwide.

There are 245,660 candidates running in the elections for the presidency, the national parliament and local councils.

For the first time since Indonesia transitioned to democracy in 1998 following the fall of President Suharto, votes for both the executive and legislative branches will be cast on the same day.

CNN’s Angus Watson and journalist Yosef Riadi in Jakarta contributed to this report.