Former Khmer Rouge second-in-command and current Case 002 defendant Nuon Chea was known to exaggerate confessions extracted from Vietnamese prisoners of war for propaganda broadcasts, the former chief of the notorious S-21 prison told the Khmer Rouge tribunal yesterday.

S-21 warden Kaing Guek Eav, better known as Duch, told the court the main point of torturing and interrogating Vietnamese prisoners was so they would confess to invading Cambodia. Their voices were recorded and broadcasted, but not before going under the editorial eye of Chea – who is facing charges of crimes against humanity, including genocide.

“He only made minor changes,” Duch said; for example, the number of firearms a Vietnamese troop confessed to bringing into Cambodia would jump from 15 to 20.

Duch was at pains to point out that “only very few” prisoners were Vietnamese civilians, but he ultimately conceded: “In principle, both civilians and soldiers had to be smashed.”

Duch – who still keeps the case file from his trial, including a list of 11,000 names of S-21 prisoners, in the Takhmao cell where he is serving a life sentence – requested information about the court’s updated list, which swelled to include 15,000 names after investigations into Cases 003 and 004.

One of the only survivors from that list, Chum Mey, gave recent testimony about the torture he suffered, such as toenail extraction and electrocution of the earlobe. “[My deputy] Hor told me that toenails were pulled off, and at the time I instructed him – I was serious about that – and I instructed him to stop that kind of practice,” Duch said.

“I authorised the electrocution, but I strictly forbade them to let any prisoner die.”

Under questioning by the prosecution, Duch said that there were no funeral rites for the smashed. “For prisoners at the time, they were buried in graves. That was against the tradition and our customs.”

Duch also elaborated on questions put to him by civil party lawyers last week, when he said Nuon Chea had ordered that four Western prisoners be burned to ash under car tyres in the street.

The prosecution is expected to probe Duch further today on a meeting he had with Case 002 co-accused and former head of state Khieu Samphan.

Meanwhile, the tribunal has received an injection of SEK 28 million (about $3.4 million) from the government of Sweden to fund the international legal costs over the next four years until 2019, it was announced last Friday.