Four sitting lawmakers suspected of taking bribes have decided to not appear at court hearings Thursday, prompting prosecutors to mull forcibly detaining them for further questioning.

A Seoul court was scheduled to hold hearings later in the day to review the legality of the arrests of the four -- Reps. Cho Hyun-ryong of the ruling Saenuri Party, and Kim Jae-yun, Shin Hak-yong and Shin Geh-ryeun of the main opposition New Politics Alliance for Democracy.

The Seoul Central District Prosecutors' Office probing the case said the four lawmakers notified the court to either postpone the hearings or they would not show up.

The prosecution office is reviewing taking measures to forcibly detain the four legislators as they are immune from arrests while the National Assembly is in session.

Cho is under suspicion of taking bribes worth 160 million won (US$156,000) from railway parts supplier Sampyo E&C in return for awarding the private company contracts since August 2008.

Kim, Shin Hak-yong and Shin Geh-ryeun have been under investigation since early August over corruption allegations as well.

Kim and Shin Geh-ryeun are each accused of taking about 50 million won in bribes from a local vocational training school earlier this year in return for helping pass a bill in favor of the school.

The passage of the bill to revise the vocational education law in April helped change the name and upgrade the status of what is now known as Seoul Art College.

Shin Hak-yong, the chairman of the National Assembly's education and culture committee, is accused of proposing a law governing privately-run kindergartens after taking some 38 million won from an association of private kindergartens. (Yonhap)