VOA常速英语:Suspected Militants Torch 27 Tankers Heading for Afghanistan

Pakistani officials say suspected militants in the country's south on Friday set fire to a convoy of tankers carrying fuel for foreign troops in Afghanistan. The attack came after the closing of a Pakistani border crossing in the northwest, following an earlier NATO airstrike in Pakistan.  The events raise concerns about mounting tensions between Washington and Pakistan, a nation the U.S. calls a key ally in the war on terror. VOA's Robert Raffaele has more.

Flames roared from the tankers, after Pakistani officials say a group of gunmen set 27 vehicles on fire. No one was killed, but officials say a similar attack elsewhere left two people dead.  Police arrested around 10 suspects in connection to this attack in the southern city of Shikarpur. 

A day earlier, Pakistan shut down a vital supply route for  NATO forces. Camera crews captured trucks and fuel tankers stopped by police at the Torkham border post in the Khyber tribal region. The bulk of fuel and other non-lethal supplies for NATO troops in Afghanistan moves through Pakistan.

U.S. Special Envoy to Afghanistan and Pakistan Richard Holbrooke on Friday took part in a foreign policy discussion in Washington. He said closing the border for very long would have a colossal impact on Pakistan's economy. "It's inconceivable to me that the closing of the routes -- the alleged closing which is not a full closing anyway -- would continue more than a short period of time," he said.

But there are obvious strains in the U.S.-Pakistani relationship. Pakistan closed the border after it says a NATO airstrike killed three of its soldiers, and anger over that and other incidents flared in parliament Friday.

Prime Minister Yousuf Raza Gilani. "If you (NATO) attack inside Pakistani territory and cause any collateral damage, we will not accept it. We will never allow you to interfere with Pakistan's sovereignty and security. If you (NATO) do not justify the attacks and do not apologize, then we will consider other alternatives. We have other options too," he said.

White House spokesman Robert Gibbs had this to say. "We will continue to work with our ally in ensuring we can do whatever is possible  to assist them in their fight against those extremists that again, not just threaten us, but threaten the existence of their own government in Pakistan," he said.

In Karachi Friday, scores of protesters took to the streets to condemn NATO strikes in Pakistan.

And Pakistan's ambassador to Belgium lodged a formal protest to NATO leaders.