Suspected militants have blown up a key rail link in the south-western Pakistani province of Balochistan.
Officials say four bombs were detonated one after the other late on Monday, destroying a bridge and a portion of railway track near the town of Sibi.
No one was hurt in the attack but train services have been disrupted.
Balochistan has been hit by a wave of violence recently blamed on armed tribesman seeking greater autonomy.
Sibi lies some 100km (60 miles) south-east of the provincial capital, Quetta.
The federal government has recently stepped up security in both places because of recent tensions.
Wave of attacks
One explosion, in Quetta last December, killed 11 people.
A militant group calling itself the Balochistan Liberation Army (BLA) has said it carried out some of the attacks.
Throughout 2004 the security situation in Balochistan deteriorated sharply -more than 30 soldiers and paramilitary personnel died in the violence.
In January there was a two-week stand-off with armed tribesmen around the Sui gas installation.
Armed clashes in the area had disrupted the supply of natural gas to much of the country.
The demands of nationalists and militants include more autonomy for the province and an end to military cantonments and huge development projects that they feel may marginalise the local Baloch population.