JAKARTA (THE JAKARTA POST/ASIA NEWS NETWORK) - The deadly 40-hour standoff at the National Police Mobile Brigade headquarters (Mako Brimob) in Depok, West Java, was the result of poor planning. The regular detention centre where the clashes took place was turned into a high-security prison to house terror detainees.

Correctional system expert Leopold Sudaryono said the Mako Brimob detention centre did not meet the basic requirements for high-security prisons set by the 2003 Law and Human Rights ministerial regulation on the designs for the country's prisons and detention centres.

"The ministry requires wall thickness to be 20 centimeters, and we could see that Mako Brimob does not have that. The regulation also requires there to be five locked doors between the inmates and the outside world. This requirement was also not met," Leopold said.

In the prison riot, which happened on Wednesday, dozens of terror detainees broke through the walls and prison bars and proceeded to the investigators' room, where they assaulted officers who were questioning new detainees.

They later seized weapons and explosive materials, which led to a 40-hour standoff between terror inmates and security forces.

The Mako Brimob detention centre opened in 2007 to serve as a temporary holding facility for police officers facing criminal charges. It is sited in the middle of a key police facility.

A number of generals have been detained at the facility, including graft suspects Susno Duadji and Suyitno Landung.

Other high-profile graft suspects included former Democratic Party treasurer Muhammad Nazaruddin and former Jakarta governor Basuki "Ahok" Tjahaja Purnama, who is serving his prison term for blasphemy.

Leopold said the addition of 156 terrorist inmates had put more pressure on the detention centre.

"This detention centre is located in the middle of the Brimob headquarters, which is surrounded by offices, a police housing complex and an armory. This was a dream location for the terrorists because they have access to weapons and civilians nearby," Leopald said, who called the facility "thick enough for outside threats, but too thin to deal with threats from the inside".

Wednesday's riot was the second in less than seven months, after a brawl in November last year, when terrorism detainees resisted efforts from police guards to search their cells for contraband, including cell phones.

The facility also has to deal with overcrowding.

"We have to admit that the detention centre suffers from overcrowding," National Police spokesman Setyo Wasisto said on Wednesday.

Three blocks, each with 14 individual cells, housed 156 terror inmates until Wednesday's riot.

"The standard operating procedure in the detention of inmates who pose a high security risk requires that each be held in separate cells, so that they can't interact with other inmates or prison guards. This is impossible at Mako Brimob," said Leopold.

Following the standoff, which came to an end Thursday morning, National Police spokesman Brigadier general Muhammad Iqbal said that 155 terror detainees were all sent to Nusakambangan prison island, located off Cilacap in Central Java.

The Law and Human Rights Ministry's director general for penitentiaries Sri Puguh Utami said only 145 inmates had been shipped to Nusakambangan, while ten others remained at Mako Brimob.

Hendra Eka, a warden at Nusakambangan prison island, said the island had a capacity of up to 3,000 prisoners.

"We can accept another 1,000 terrorism detainees, so 150 is no problem," he told the Post.

The terror inmates arrived on Nusakambangan prison island on Thursday afternoon under the close watch of 400 security personnel.

Nusakambangan prison island, which comprises seven prisons, currently houses 1,500 high-risk prisoners, including 70 terrorism convicts and 50 death row inmates.