Tom McCawley, Jakarta – Two bombs were discovered at the Indonesian attorney general's office in Jakarta on Wednesday, inflaming fears of political uncertainty and helping to drive the rupiah to its lowest closing price for more than a year.

Detectives and bomb specialists found the two devices near the site of a blast on Monday night, which was dismissed by attorney general Marzuki Darusman yesterday as a "terror tactic."

After opening at Rp8,975 to the US dollar, the rupiah weakened to Rp9,360 by the close, its lowest level since March 1999. "Markets are very concerned by statements from the president, by Wednesday's bomb explosion at the attorney general's office, and the discovery of two more bombs," Andi Wijaja, a currency trader at HSBC, said yesterday.

Abdurrahman Wahid, Indonesian president, said on Tuesday that several legislators are to be questioned as witnesses in an investigation into the causes of regional unrest in Indonesia.

Officials at the attorney general's department say they have received a series of anonymous threats in recent months relating to politically sensitive investigations. Mr Marzuki has ordered a range of official probes spanning military human rights abuses in East Timor, a large banking scandal and official corruption under the government of former President Suharto. Police have detained one man for questioning over the blast on Monday night but have released no further details.

"The political situation is scaring the markets," said Beni Rusnadi, a currency trader with local bank BNI 46. "But looking at the country's decent economic fundamentals, and support for the IMF there's no reason for the rupiah to be weak." Currency traders said demand for dollars was rising as companies complete debt restructuring and make interest payments on loans.

Kwik Kian Gie, co-ordinating economics minister, was quoted as saying he would meet with central bank governors to "boost the rupiah". But Miranda Goeltom, deputy governor of the central bank, which was granted greater independence under a 1999 law, said "intervention was unlikely to be effective," although she did not rule it out. The rupiah's fall is of particular concern to Indonesia's corporations with US-denominated debts.

The International Monetary Fund, which is backing a economic restructuring package for Indonesia, has praised recent improvements in Indonesia's macroeconomic fundamentals.