Singapore disclosed Wednesday it arrested 27 Bangladeshi construction workers late last year for supporting "the armed militant ideology of terrorist groups" and deported 26 of them.

The workers were being groomed to return to their home country to wage holy war, and some had studied booklets on assassination techniques, the Ministry of Home Affairs said.

The arrests were made under the tough Internal Security Act.

"They supported the armed militant ideology of terrorist groups like Al-Qaeda and the Islamic State in Iraq and Syria," the ministry said in a statement.

It said the Bangladeshis, arrested between November 16 and December 1 last year, worked in construction in Singapore, where labourers live in often cramped dormitories.

"The group members took measures to avoid detection by the authorities. They shared militant-related material discreetly among themselves, and held weekly meetings and gatherings where they discussed armed jihad and conflicts that involved Muslims," the ministry said.

The group was also actively recruiting members, it added.

The ministry said that "while several members of the group had considered carrying out armed violence overseas, they were not planning any terrorist attacks in Singapore".

It said 26 had been deported. The remaining Bangladeshi is serving a jail sentence for attempting to flee Singapore after learning about the arrests of the other group members.

He will be repatriated to Bangladesh after he completes his sentence. The man was said not to have been a member of the group but was "in the process of being radicalised".

Group members were encouraged to return to Bangladesh and "wage armed militant" against the government there, while some had sent money to terror-linked entities in their country, according to the statement.

The ministry said the 27, aged between 25 and 40, possessed radical and militant-related materials, including footage of children undergoing training in what seemed to be militant camps.

A document that contained graphic images and instructions on how to carry out "silent killings", using different methods and weapons, was was also being shared among members.

An extract from a document found in their possession, entitled "Techniques of Silent Killing" and released by the ministry, showed three drawings of a man approaching a seated victim from behind, covering the victim's mouth with one hand and stabbing him with a knife.

Singapore authorities in late 2001 foiled an attempt to carry out bomb attacks on US and other foreign targets in the city-state, arresting several suspects in the process.

"The government takes a very serious view of any form of support for terrorism and will take firm and decisive action against any person who engages in any activity in support of terrorism," the ministry said.

"Foreigners are guests of our country and they should not abuse this privilege and use Singapore as a base to import their own domestic political agenda and carry out activities in pursuit of such an agenda."