[Nulgath]

A secretive gathering of Islamic State (IS) supporters at a mosque in central Jakarta has been witnessed by the ABC.

It is the first time a foreign film crew has been present at the meeting, which is understood to be part of a recruitment drive in the Indonesian capital.

After a tip-off and a lengthy search, the As-Syuhada mosque was located down a street not big enough for cars.

An ABC cameraman — an Indonesian national and Muslim — gained access to the meeting and while attempts were made to stop him filming, what he managed to capture is clear.

"They declare that territory as Islamic State where God's law is upheld fully and where there isn't any intimidation from foreign countries," hardline cleric Syamsudin Uba told the gathering.

"And based on their sacrifice of their blood and wealth they declare an Islamic State."

He has previously been detained for his IS teachings but there are inadequate laws in Indonesia to stop his recruitment drive.

"Even though the infidels wouldn't acknowledge it (an Islamic state), even though the United Nations wouldn't acknowledge it," he said during the sermon recorded by the ABC.

"Muslims don't need that, Muslims only want the blessing from God, in a state where the laws of God are implemented fully. Even when the infidels don't like it."

Recordings from another camera filming at the meeting were later uploaded as IS propaganda on YouTube.

Clearly visible in the footage is the black flag often used by the IS militant group.

During the filming another cleric urges his followers to travel to Syria for a better life.

"When you get there soon, God willing, you won't have to pay rent, you don't have electricity and water bills," he said.

"You will get monthly food expenses, a monthly allowance, free health care and medicines."

The man even promised that interracial marriage would be tolerated there.

Islamic State preachings have taken place at five Jakarta mosques

When the sermon was over and the threat removed, the ABC returned to ask questions about the preachings in the mosque.

The caretaker, Tahmid, insisted he had no idea an IS recruitment drive had taken place there.

"They gave us short notice," he told the ABC.

"We, the mosque caretakers, didn't know what the discussion was really about."

The ABC knows of at least five mosques in Jakarta where IS preachings take place.

One is in the wealthy suburb of Menteng — the home of many senior diplomats.

Similar meetings have been held at the Al Fataa mosque and one of the terrorists involved in last month's deadly attack in Jakarta, Afif, is said to have prayed there.

Farihin Kandai, a former member of Jemaah Islamiah who has served jail time for terrorism offences, said he was trying to have the IS preachings stopped.

"Security called me and shared their concern about ISIS supporters blooming in mosques across Indonesia," he told the ABC.

"Then they asked me to eliminate the activities."

But far from being eliminated, support is growing, and there is concern in the wake of last month's terrorist attack not enough is being done to stop the spread of the IS message.