CAIRO: A senior Egyptian judge hanged himself in custody Monday a day after his arrest in connection with an investigation into a corruption case, his lawyer said.

Wael Shalabi, secretary general of the council of state, an administrative court, was taken in for questioning Sunday, his lawyer Sayed el-Beheiry told AFP.

After questioning him, prosecutors ordered that he be detained for four days pending further investigation, he said.

Shalabi's arrest came days after the Administrative Control Authority responsible for tracking corruption in state institutions arrested the council of state's chief procurement officer, Gamal el-Labban.

The public prosecutor's office issued a gag order on publishing details of the case shortly after news broke about Shalabi's death.

"He faced a lot of pressure" during interrogation on Sunday when he "denied accusations that were directed at him," Beheiry said.

"He went to the bathroom, attached his scarf to the water-heater and hung himself.

"This is negligence on their part because he was subject to psychological pressure," the lawyer added.

An autopsy showed that Shalabi had committed suicide, and an investigation has begun, Beheiry said.

After Labban was arrested, Shalabi submitted his resignation to the council of state, and this was accepted on Saturday.

Prosecutors had also ordered Labban's detention for four days pending an investigation.

It is rare for Egypt to investigate alleged corruption inside its judicial institutions.

Watchdog Transparency International ranks Egypt as 88th out of 168 countries on its corruption perceptions index.