Workers being held hostage by Russian forces at the site of the Chernobyl nuclear power plant in northern Ukraine have been playing the Ukrainian national anthem every morning in defiance of their captivity, The Wall Street Journal reported on Tuesday.

Russian forces have held more than 200 employees at the plant at will since they seized control of the site on the first day of the invasion of Ukraine.

The poorly-fed technicians and support staff are battling immense exhaustion after spending roughly 500 hours since February 23 on the job at the site of the world's worst nuclear-power disaster.

Workers are starting to defy their captivity.

The Journal reported that workers at Chernobyl blast the national anthem of Ukraine every morning at 9 a.m.

Ukrainian workers stand up with their hands over their chests as the anthem plays, according to the newspaper.

The Journal reported that trapped staffers were arguing with their Russian abductors over the invasion of Russia.

The employees are sleeping on chairs near machines and on mounds of clothes by the work stations, according to the Journal.

Their phones have been taken away, but in one-minute calls that the Russian troops allow the staffers to make to family members, they have spoken of extreme fatigue, dizziness, nausea, and terrible headaches.

According to the Journal, shift supervisor Valentin Heiko recently told managers in a phone call that the psychological situation was getting worse.

Heiko said that everyone wants to go home, but they need to stay.

Russian President Putin launched a war against Ukraine on February 24. His advances have stopped in the face of Ukrainian resistance.

Russian forces have intensified their bombing and shelling of Ukrainian cities.

Insider is covering the developments of the Russian invasion of Ukraine.