SEOUL, Dec. 8 (Yonhap) -- Police said Thursday that they have questioned aides to two more conservative lawmakers about a cyber attack that temporarily paralyzed the Web site of the national election watchdog in October.

The National Police Agency said it had an overnight interrogation of a former secretary of National Assembly Speaker Park Hee-tae and an aide of Chung Doo-un, a two-term legislator of the ruling Grand National Party (GNP), to see if they were also behind the attack on the morning of the Oct. 26 by-election.

Park, who currently has no party affiliation, was formerly a member of the ruling party.

The large-scale distributed denial-of-service (DDoS) attack paralyzed the Internet site of the National Election Commission (NEC) for two hours on the morning of the by-election for the Seoul mayorship and many other governmental posts. The attack also targeted the official Web site of Park Won-soon, then the leading Seoul mayor candidate who ended up winning.

Opposition parties have raised suspicions that some from the conservative party masterminded the attacks in a bid to prevent the liberal-minded Park's victory.

The hacking mainly blocked access to information on polling station locations on the NEC Web site. As a result, the attacks could have undercut voting among younger generations, the main force behind Park's victory, according to analysts.

The police suspect a man surnamed Kong, a low-rank secretary of GNP Rep. Choi Gu-sik, conducted the attacks with help from professional hackers. The lawmaker and the aide have both denied their involvement.

Investigators previously found that Kong had several phone conversations with the ex-aide to Park Hee-tae while the attacks were being waged. Kong, Park's former aide and Chung's aide also went drinking together after having dinner with another GNP lawmaker's aide the night before the by-election, according to police.

Police suspect that the drinking session may hold key clues to the hacking scandal.