Police in Jakarta have discovered two more bombs following the explosion of a first device, including one addressed to a former high-ranking officer with Indonesia's crack anti-terrorism unit Densus 88.
A security guard and three police officers, including one who lost his arm, were wounded when the first bomb detonated at an office building in east Jakarta just after 4pm (10pm NZT) on Tuesday.
It was addressed to Ulil Abshar Abdalla, an outspoken critic of Islamic hardline groups and a senior member of Indonesian President Susilo Bambang Yudhoyono's Democratic Party.
However, it appears whoever sent the bomb was off target as Abdalla, the former director of the Institute for Studies on Free Flow of Information (ISAI) which has its offices at the building where the bomb exploded, has not worked there for some years.
The Muslim scholar later told local television station, MetroTV, that the incident was "politically motivated".
Hours after the explosion, police found another two parcel bombs similar to the first, including one sent sent to the offices of the National Narcotics Board and addressed to its chief, Brigadier General Goris Mere.
Goris is a former high-ranking officer with Densus 88, Indonesia's anti-terrorism unit which is funded by Australia and the United States.
The third bomb was sent to a politician at another location in Jakarta.
National Police spokesman Inspector General Anton Bachrul Alam said it appeared the bombs were sent by a terrorist group, the Jakarta Globe reported.
"Who else is capable of creating such a bomb if not an expert from the old terror cells?" he said.
The discovery of the bombs comes as radical Muslim cleric Abu Bakar Bashir faces trial on terrorism charges related to the discovery of a paramilitary training camp in Aceh last year.
Bashir, the founder of Jemaah Islamiah, the group responsible for the 2002 Bali bombings which killed 202 people including 88 Australians, referred to Goris last month during his terrorism trial.
"Please know that the allegation of terrorist was deliberately spread by God's enemy - the zionists and their allies America and Australia, and followed by Detachment 88 (Densus 88)," he told the court at the time.
The first bomb exploded as one of the police officers at the scene examined the package, which was similar in make to the other two devices found later.
The bomb was contained in a book with its pages hollowed out, and was accompanied by a letter addressed to Abdalla.
Graphic footage aired on Indonesian television shows the moment Dodi Rahmawan lost his arm when the device exploded. He can be seen hosing down the package and flicking through the pages of a book before the blast.
He remains in a critical condition in the Cipto Mangunkusumo hospital.
Two other police officers and one security guard were also injured in the blast.
Abdalla also founded the group Jaringan Islam Liberal (Liberal Islam Network) while with ISAI as part of efforts to counter the growing influence and activism of militant and radical Islam in Indonesia.
It describes itself as "a community which is studying and bringing forth a discourse on Islamic vision that is tolerant, open and supportive for the strengthening of Indonesian democratisation".
Abdalla is also a member of the national leadership board of the Democratic Party, which he joined after President Yudhoyono won his second term in office in 2009.
"I have always been advocating religious freedom," he said on Tuesday night.
The attempted attack comes amid an upswing in religious violence and intolerance in Indonesia including attacks on members of Ahmadiyah, a minority Muslim sect.
The president has made statements recently condemning attacks against Ahmadis after three were killed during a violent rampage involving 1500 people in Cikeusik in west Java's Banten province last month.