By Hyunsu Yim and Jack Kim
SEOUL (Reuters) - South Korean police tried to search President Yoon Suk Yeol's office on Wednesday but have not been able to enter the main building, Yonhap news reported as an investigation into the U.S. ally's decision to declare martial law widened.
The attempt to search the presidential office significantly escalates the investigation against Yoon and top police and military officers over the Dec. 3 martial law declaration that plunged the country with Asia's fourth-largest economy into a constitutional crisis.
Yoon is now the subject of a criminal investigation into insurrection allegations and is banned from leaving the country, but he has not been arrested or questioned by authorities.
A presidential security service official said earlier on Wednesday that the police raid of Yoon's office was under way, confirming media reports at the time. Yonhap later said investigators at the presidential compound had not yet entered the main building.
Yonhap said police had not managed to agree with the Secret Service on the method of the seizure and search. Police declined to comment.
"We are responding based on the law and past government cases," a presidential office official said and denied that the office was opposing the search.
Former Defence Minister Kim Yong-hyun, a close confidant of Yoon, and two senior police officers including the national police chief have been arrested on charges of insurrection as part of the investigation.
Kim attempted suicide using a shirt and underwear late on Tuesday night at a detention centre where he is being held, a Justice Ministry official told parliament.
He was now under observation and his life was not in danger, the official added.
Kim has resigned and apologised for his part in the short-lived imposition of emergency rule, saying he alone was responsible.
Soon after Yoon's late-night declaration of martial law, lawmakers including some members of his own party voted to demand the president immediately rescind the order, which he did hours later.
REVIEWING ARREST
The president, who has not been seen in public since Saturday, was not believed to be in the presidential compound, Yonhap said. The official residence is at a separate location from the office.
Oh Dong-woon, head of the Corruption Investigation Office for High-ranking Officials and one of the agencies now investigating the martial law debacle, said his office was "willing" to arrest Yoon if required.
Earlier on Wednesday, national police chief Cho Ji-ho became the latest top official to be arrested, accused of deploying police to block lawmakers from entering parliament, Yonhap said.
Calls for Yoon's arrest grew after top military and government officials said he ordered troops to enter parliament on Dec. 3 and stop lawmakers from voting to reject martial law.
Kwak Jong-geun, commander of the Army Special Warfare Command, told a parliament committee on Tuesday that Yoon had ordered troops to "break the door down right now and get in there and drag out" lawmakers.
Yoon's then-defence minister, Kim, has also been accused by military officers of issuing the same order.
LEADERSHIP CRISIS
Yoon's grip on power is looking increasingly precarious by the day. Yoon's office said on Tuesday it had "no official position" when asked who was in charge of the country.
The leader of the president's People Power Party (PPP) said Prime Minister Han Duck-soo would manage state affairs while the party looked for an "orderly" way for the president to resign.
The constitutional legitimacy of that arrangement has been questioned by opposition parties and some legal scholars.
The opposition Democratic Party (DP) said it planned to introduce a new bill to impeach Yoon on Wednesday with a vote on Saturday, a week after its first impeachment vote was defeated.
Since then, some members of the president's party have spoken in favour of the motion. Only eight PPP members would need to vote for impeachment for it to pass with the opposition's full support.
"The impeachment train has left the platform. There is going to be no way to stop it," DP leader Lee Jae-myung said at a party meeting.
Kim Jae-sub, a PPP member who joined his party's boycott of the first impeachment vote, said he would vote for the motion this time and urged his party to do the same.
If parliament votes to impeach, the Constitutional Court then deliberates the case and decides whether to remove the president from office.
The country's metal workers' union, including workers at the Kia Corp automakers, has declared a protest strike for Wednesday. Members of financial institutions including the Bank of Korea plan to join a protest rally on Wednesday.
(This story has been refiled to add the missing word 'and' in paragraph 6)