South Korea’s intelligence service said it found North Korean attempts to infiltrate the country’s election system, which the state election commission has denied.

The National Intelligence Service said Thursday it notified the National Election Commission of North Korean hackers trying to penetrate the state election organizer’s networks, confirming the ruling People Power Party claims a day prior.

Some ruling party lawmakers suggested that while the intelligence service warned the election commission of the North Korean activities and urged security measures, no action was taken.

One of them told The Korea Herald that out of the eight known hacking attacks against the election commission in the past two years, seven were believed to have been by North Korean hackers.

Ruling party lawmakers on the intelligence and interior committees are calling to convene plenary sessions next week to summon and grill election commission officials to look into the possible North Korean hacking.

“North Korea’s attempts to tamper with our national election system is a serious threat to our democracy,” said People Power Party lawmakers on the interior committee, including ruling party leader Rep. Kim Gi-hyeon, in a joint statement.

To date, the election commission has denied that it was informed of North Korean hacking attempts, or that its networks had been exposed to such activities.

“There is no truth to the claims that the intelligence service notified the election commission of the commission’s servers being infected by North Korean phishing e-mails or malicious codes,” it said in a statement on Wednesday.

“It is impossible to manipulate vote count results,” it added, explaining that the commission’s ballot-sorting systems are run internally, and therefore safe from hacks.

In a phone call with The Korea Herald on Thursday, an election commission official said that the commission has “no further comments to add” to the statement released the day before.