By Nick Hawton
BBC News, Sarajevo
Security has been stepped up at embassies and foreign agencies in Bosnia following the arrest of two men accused of planning a suicide attack.
Islamists have previously been suspected of using Bosnia as a base
The two individuals, who have been detained under anti-terrorism laws, are being held in Sarajevo.
One of them is said to have recorded a video reciting Islamic prayers which may have been intended to be found following his death.
They were arrested last week but details are only now emerging.
The two men hold Swedish and Turkish citizenship but are believed to have originally come from the former Yugoslavia.
According to sources close to the investigation, they were carrying explosives at the time.
Weapons and other military equipment were found at premises linked to the men.
There is no indication as to what the target of any attack would have been.
There are 7,000 European Union peacekeepers stationed in Bosnia as well as several international aid agencies.
The two men are being held in prison in Sarajevo while the investigation continues.
A third man, a Bosnian, was also arrested under anti-terrorism laws but is being held at separate facilities.
The chief international envoy to Bosnia, Lord Ashdown, described the matter as serious but said the arrests showed that Bosnia was a capable partner in the international fight against terrorism.
In the past there have been suspicions that Islamic extremists may have used Bosnia as a base, but such suspicions have never been confirmed.