Former President Lee Myung-bak has been asked to appear for questioning next week over a string of allegations of bribery and other irregularities, officials said Tuesday.

The Seoul Central District Prosecutors' Office subpoenaed Lee to come to the office for questioning as a suspect at 9:30 a.m. on March 14, officials said.

"It is essential to investigate Lee in order to uncover the truth in a transparent and efficient way," a prosecution official said. "We're not considering calling him in for questioning multiple times."

The official also said prosecutors have collected enough investigative information so far and that it's time to question him face-to-face.

"We will try to be sufficiently polite toward the former president, but what's important is to conduct an investigation in a thorough and transparent manner," the official said.

Lee expressed a willingness to comply with a summons.

"As the prosecution served a summons, he will comply with it as a matter of course," an aide to Lee said. "Former President Lee has no intention of evading an investigation."

But the aide indicated that Lee wants to reschedule the questioning.

"March 14 is a date that was notified unilaterally by the prosecution," the aide said. "(Lee) wants to fix a specific date for questioning through discussions with the prosecution."

Lee, who was in office from 2009-2013, is facing suspicions that presidential aides received illicit money worth at least 1.75 billion won ($1.63 million) from the state intelligence agency at his instruction. While indicting one of Lee's closest aides last month, prosecutors described Lee as the main culprit.

Lee is also at the center of a ballooning scandal involving his brother's auto parts manufacturer, DAS. Prosecutors suspect that Lee is the real owner of the company and has used it as a channel to create slush funds, among other irregularities.

Should Lee comply with the summons, he will be the fourth former president to appear for questioning as a suspect after former President Roh Tae-woo did so in 1995, Roh Moo-hyun in 2009 and Park Geun-hye last year. Former President Chun Doo-hwan refused to comply with a 1995 summons and was later arrested.

Before serving the summons, the investigation team briefed Prosecutor General Moon Moo-il on how the investigation has gone so far, and Moon approved the team's plan to summon Lee, sources said.

Lee has denounced the investigation as political retaliation by the administration of President Moon Jae-in over the death of late former President Roh Moo-hyun. Roh killed himself in 2009 when Lee was in office amid a corruption investigation that forced him to appear for questioning, a humiliation that many believe led to the suicide.

Lee's associates have claimed that the government of President Moon, a key Roh ally who served as Roh's chief of staff, is trying to force the same humiliation back on Lee. Prosecutors and presidential officials flatly reject such claims.(Yonhap)