Former United Nations Secretary-General Ban Ki-moon, who is highly expected to soon announce his bid in the upcoming presidential election, is facing mounting pressure over bribery allegations involving his family members.

The criticism came not only from the progressive opposition, but also from the ruling conservative Saenuri Party and its spin-off Bareun Party, both of which have been seeking to recruit Ban as their candidate in the presidential race.

“Though Ban may feel it is unfair that he should be influenced by the wrongdoing of his family member, he should explain the matter to the people,” said Jeong Yong-ki, chief floor spokesperson of the Saenuri, in a written statement.

Rep. Chang Je-won of the Bareun Party underlined Ban’s responsibility as a public figure, alluding to the scandal involving President Park Geun-hye and her aides.

“We cannot let the people face another distress over the president’s family and friends,” he said.

The United States has asked South Korea to arrest Ban Ki-sang, the younger brother of the former UN chief official, on charges of bribery. The younger Ban’s son Joo-jyun, too, was indicted on the same charges.

Ban’s brother and nephew are accused of attempting to hand over some $500,000 to an official from the Middle East to sell off a building located in Vietnam and owned by a South Korean construction firm, Keangnam Enterprises.

The disputed company was owned by Sung Woan-jong, a businessman who committed suicide in 2015, leaving behind a series of allegations that he had handed over bribes to a number of ruling party politicians.

Ban’s aides apologized over the controversy, but they denied having any knowledge of the case.

“We hope that the given procedures are carried out in a strict and transparent manner, so as to eliminate all doubts once and for all,” Ban’s team said through a press release.

The former top UN official, whose term ended in December last year, returned to his home country on Jan. 12, kindling expectations on his imminent presidential bid as a conservative candidate.

He has not made an official announcement, but upon his return, the former top diplomat immediately embarked on what was seen as a preliminary stage to an election campaign, visiting key strategic places across the nation and increasing contact with the public.

By Bae Hyun-jung (tellme@heraldcorp.com)