Indonesia has raised its security in Batam following the arrest of six suspected militants on Friday, who allegedly tried to hit Singapore's Marina Bay with rockets fired from the island.

Batam Pos newspaper reported on its website on Saturday that armed men are patrolling the Hang Nadim airport in Batam.

"We have been monitoring the situation since the morning", the airport's commercial department chief, Dendi Gustinandar told the newspaper.

Batam Pos also reported that barricades have been put up at the main gate of the police complex and police officers were on sentry duty.

Indonesian anti-terror police arrested six men on Friday for plotting a terror attack on Singapore. Officials said they belonged to the KGR or Katibah Gonggong Rebus, or Cell GR and were apparently influenced by Muhammad Bahrun Naim, a Syria-based Indonesian militant.

"We arrested six people from a terror group. We may have never heard of this name previously, it's KGR or Katibah Gonggong Rebus, from Batam," national police spokesman Agus Rianto told The Straits Times.

In response to this terror threat, Singapore's Deputy Prime Minister Teo Chee Hean said the police and other security agencies in Singapore have been stepping up both inland and border security measures.

Ansyad Mbaai, the former chief of Indonesia's influential anti-terror agency or BNPT, said: "The name of the group indicates how militant groups in Indonesia have become splintered and divided, and the members could care less about being part of a big-named network such as Jemaah Islamiah (JI)".

"Even one or two people could form a group. Names are no longer important to them," he added.

Ansyaad also said that these Indonesian extremists do not identify with terror groups. They believe in their causes.

"They sympathise with Muslims who are oppressed overseas. And whoever has fought there in Syria, whoever is the most brutal or has money, that person is idolised and becomes the leader," he said.

He said, "The Indonesian militants now can't distinguish Jemaah Islamiah from Al-Qaeda or ISIS. To them, these groups are the same."