Five intelligence employees were killed near the Jordanian capital of Amman on Monday in what the government has called an act of terror.

The five died after an unknown number of militants attacked an intelligence office in a Palestinian refugee camp on the first day of the Muslim holy month of Ramadan.

"The intelligence agency office in the Baqaa camp was the target of a cowardly attack shortly before 7:00 am today that left five agents dead," said government spokesman Mohammed Momani.

Momani added that security forces were already investigating who was responsible for the "terrorist attack" but did not clarify the nature of the violence.

Media reports have said that three intelligence agents along with an office handyman and a receptionist were among the dead. One security source told French news agency AFP that a lone gunman had opened fire with an automatic weapon as the workers were starting their shift. He then escaped, the source said.

Such an incident is rare in Jordan, a key regional member of the US-led coalition against so-called "Islamic State" (IS) extremists. In December 2014, a Jordanian pilot was captured by IS, with the terrorists later releasing a grisly video of the man being burned alive.

The Baqqa refugee camp where the attack occurred is the largest in Jordan, a country of seven million inhabitants, two million of them Palestinians. Many of these people are descendants of people who fled Palestine after the creation of Israel in 1948.

Today, Baqqa houses some 70,000 refugees.

es/jm (AFP, Reuters)