Syrian media yesterday blamed Saturday's car bomb attack in the capital Damascus on outside forces as the government launched an investigation to track down those responsible.

The bomb, which killed 17 people and injured 14 others - all civilians - exploded close to a building used by military intelligence and a checkpoint on a road to the airport. The area is near an important Shia shrine, where many Iraqis live.

General Bassam Abdel Majid, Syria's interior minister, called the blast "a terrorist act" but said it was too early to say who was responsible.

However the Al-Thawra newspaper, which is close to the government of Bashar alAssad, the president, said the bombing had been planned abroad and carried out by foreigners.

It called for measures to secure the borders. Syria this month sent thousands of soldiers to the border with Lebanon, in a move it said was intended to counter smuggling.

Relations between the two countries have been tense since Syria withdrew its troops from Lebanon in 2005 and an anti-Syrian coalition came to power in Beirut.

Large bomb attacks are rare in tightly controlled Syria, although small fire-fights and explosions - including one near the US embassy in 2006 - and targeted attacks on officials and militant commanders occur more frequently.

However, in the 1980s Syria experienced a period of violence when the fundamentalist Muslim Brotherhood campaigned against the government.

Ali Sadreddine Bayanouni, the head of the Syrian Muslim Brotherhood in exile, condemned Saturday's blast but said "there is a mood of oppression in Syria and this breeds extremism".

Another Syrian opposition source said he did not believe outside forces were responsible for the attack, "because the regime controls everything".

It was more likely that the blast was the result of rivalries within Syria's security services.

Rumours of such rivalries emerged last year after the killing in Damascus of Imad Moughniyeh, a prominent commander of Lebanon's Hizbollah movement. Hizbollah blamed Israel, but Israel has denied any involvement.

In July this year, Mohammed Suleiman, a senior Syrian general, was killed by a sniper in the coastal city of Tartous.

Gen Suleiman was involved in the probe by the International Atomic Energy Agency, the United Nation's nuclear watchdog agency, into a Syrian facility that was hit by an Israeli air strike last year.

The US has claimed Syria was building a nuclear reactor on the site with North Korean help.