Kidnapped CBC journalist Mellissa Fung said she was kept in an underground chamber southwest of Kabul for nearly four weeks before being released on Saturday.

In this picture released by the National Directorate of Security (NDS), Mellissa Fung talks on the phone as NDS chief Amrullah Saleh looks on at his office in Kabul. (National Directorate of Security/Associated Press)

Fung described her 28-day ordeal in a videotaped interview with Afghan National Directorate (NDS) security director Amrullah Saleh, a day after she was freed by Afghan intelligence officers.

"The cave was very, very small," said Fung, who is seen in the video wearing a head scarf and a green army camouflage jacket. "It was about five and a half feet deep. It led to a tunnel and then a room."

She said the area where she was held was so small she could barely stand. On the video, released Sunday, she drew a diagram of the conditions in which she was kept.

"When did they start to mistreat you badly?" Saleh asked her.

"They never really, just when they chained me," she replied.

Fung, who's 35 and was raised in Vancouver, said her captors stayed with her for the first three weeks but in the last week, she was left on her own with her hands and feet chained.

She said her captors never hurt her but that she was kept blindfolded.

In the video, Fung can be seen telling Ron Hoffman, Canada's ambassador to Afghanistan, that she's not hurt and that she hopes people won't make "a big fuss" over her situation.

CBC News publisher John Cruickshank said on Sunday that the abduction was planned by armed men who were aware Fung was working on a news story with the help of a fixer and they saw an opportunity to grab her while eluding police.

"She had been in a refugee camp. She'd been doing some reporting on conditions there and on difficulties in Kabul, and essentially, as she left the camp, within a couple of blocks of a police station, they pulled up in a van, jumped out and overpowered her and took her," he said.

The journalist was captured on Oct. 12 and held in a dangerous Taliban-controlled region of Wardak province, about 50 kilometres southwest of Kabul, before Afghanistan's intelligence agency secured her release on Saturday.

The raid to free her came shortly after a threatening phone call earlier Saturday by one of the kidnappers, saying Fung would be killed if a ransom went unpaid or if several people in police custody were harmed, the CBC's Susan Ormiston reported.

"Around 8:30 p.m. local, we successfully raided a house … and rescued Ms. Fung in very good health condition," an official said at a news conference.

Afghan intelligence agents confirmed Sunday that no ransom was paid, and they also said they have arrested three people, described as secondary suspects. One of the key men involved may have fled the Afghanistan, Ormiston said.

The abductors were believed to be criminals, not Taliban insurgents.

Fung was on her second tour in Afghanistan and had been in Kabul nearly a month when she was taken. Her driver and translator, or "fixer," were overpowered, and later government authorities detained them for questioning.

The CBC's longtime Afghan fixer remained in detention throughout Fung's captivity and was still being held by Afghan authorities Sunday. Cruickshank said he's hopeful the man will be released soon.