A Seoul court has issued an arrest warrant against South Korea's suspended president Yoon Suk Yeol over his attempt to impose martial law on 3 December.

The warrant comes after Yoon, who is facing several investigations on insurrection and treason charges, ignored three summonses to appear for questioning over the past two weeks.

On Sunday night, investigators sought an arrest warrant for Yoon on charges of insurrection and abuse of power - a move that his lawyer described as "illegal".

South Korea has been in political crisis since the short-lived martial law declaration, with Yoon and a successor both impeached by parliament.

Yoon is South Korea's first sitting president to face an arrest.

Investigators have until 6 January to execute the warrant and can request for an extension.

It is unclear, however, if investigators will be able to execute the warrant as they may be thwarted by his security team and protesters.

The presidential security service had earlier blocked investigators from entering the presidential office grounds and Yoon's private residence to conduct court-approved searches.

In the past, South Korean authorities have given up arrest attempts against prominent politicians after their aides and supporters have physically blocked the police.

On Monday, Yoon's legal team said that investigators had no authority to arrest him, as declaring martial law was within the president's constitutional authority.

Yoon had earlier defended his decision to declare martial law and vowed to "fight to the end" - though he also said that he would not avoid his legal and political responsibilities.

His lawyer, Yun Gap-geun, said that Yoon's failure to comply with the earlier three summonses was due to "legitimate concerns".

Yoon's whereabouts are not publicly known, but he has been banned from leaving the country.

While he has been suspended from presidential duties since 14 December after lawmakers voted to impeach him, he can only be removed from office if his impeachment is sustained by the country's constitutional court.

There are currently only six judges on the constitutional court's nine-member bench. This means a single rejection would save Yoon from being removed.

Opposition lawmakers had hoped the nomination of three additional judges would improve the odds of Yoon getting impeached, but their proposal was vetoed by prime minister Han Duck-soo last week.

The opposition has since then voted to impeach Han, who had stepped in as acting leader after Yoon was suspended.

Now, they are threatening to do the same to finance minister Choi Sang-mok, who currently serves as both acting president and acting prime minister.

Additional reporting by Kelly Ng