Instituto Federal Electoral/Handout/via Reuters TV

Former Playboy model and presidential debate assistant Julia Orayen hands out cards to the four candidates during a televised debate Sunday night at the Federal Electoral Institute in this still image taken from video.

A former Playboy model clad in a revealing white dress stole the show at a somber presidential debate in Mexico focused on the economy and drug-related violence.

Wearing a tight-fitting white dress with a cut below the neckline to show much of her cleavage, Julia Orayen was working as an assistant on the televised debate.

At the start of Sunday night's debate, Orayen walked in front of the camera to hand out cards to the four candidates, creating an immediate stir on online social media.

The appearance lasting a few seconds quickly began trending on Twitter, generating thousands of mentions. Mexican newspaper Excelsior declared her the online winner of the debate.

"The best was the girl in white with the cleavage at the beginning," tweeted former Mexican Foreign Minister Jorge Castaneda, who is also a New York University professor.

At least one candidate was seen gawking at Orayen's posterior from the dais. Gabriel Quadri, who is drawing single-digit support as the candidate of the New Alliance party, said her appearance made him nervous.

"It is impossible not to concentrate your attention on a woman so spectacular," Quadri told MVS Radio.

While many Mexicans celebrated Orayen, others condemned the Federal Electoral Institute (IFE) for the incident, saying it had undermined the seriousness of the debate.

The IFE later issued a statement apologizing to the citizens of Mexico and the candidates for the "production error associated with the dress of an assistant."

A Twitter account in Orayen's name has picked up more than 7,000 followers since the two-hour debate.

Orayen posed nude for the Mexican edition of Playboy in 2008, a spokesman for the magazine said.

Reuters and The Associated Press contributed to this report.

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