South Korea authorities attempt to arrest impeached President Yoon

Authorities entered impeached South Korean President Yoon Suk Yeol's compound on Friday to execute an unprecedented arrest warrant, evading a crowd of protesters outside, but were confronted with presidential security forces.

It was unclear whether the Presidential Security Service (PSS), which has previously blocked access by investigators with a search warrant to Yoon's office and official residence, would try to stop him being arrested.

Yoon is under criminal investigation for insurrection over his December 3 martial law attempt that stunned South Korea, Asia's fourth-largest economy and one of the region's most vibrant democracies.

An arrest would be the first for an incumbent South Korean president.

Officials from the Corruption Investigation Office for High-ranking Officials (CIO), which is leading a joint team of investigators that include the police and prosecutors, had arrived at the gates of Yoon's compound shortly after 7 a.m. (2200 GMT Thursday), according to Reuters witnesses.

The CIO vehicles did not immediately enter the compound, partly due to a bus blocking the driveway.

Some CIO officials later filed through an opened gate on foot and past the bus, but then briefly faced another bus and an armoured vehicle further up the driveway, before they were moved.

Once inside the compound, the CIO and accompanying police faced cordons of PSS personnel, as well as military troops seconded to presidential security, media reported. South Korea's Ministry of National Defense said the troops were under the control of the PSS.

Yonhap news agency cited the head of the PSS saying the authorities are not allowed to search Yoon's residence.

Yoon's lawyer said in a statement on Friday that execution of an invalid arrest warrant against Yoon is unlawful, and they will take legal action, without elaborating.

Protesters gathered in the pre-dawn hours near the residence, with the numbers swelling into the hundreds amid media reports that investigating authorities would soon try to execute the arrest warrant that was approved on Tuesday after Yoon refused summons to appear.

"We have to block them with our lives," one was heard saying to others.

Some chanted "President Yoon Suk Yeol will be protected by the people," and called for the head of the CIO to be arrested.