Two US senators just back from a trip to Afghanistan and Pakistan said Wednesday that the coming weeks will show whether Islamabad can be a reliable ally against extremists.

"It does feel, at times, like Pakistan is playing both the role of fireman and arsonist in Afghanistan," said Democratic Senator Tom Udall, a member of the Senate Intelligence Committee.

"The next few weeks will demonstrate whether or not we can work together effectively with the government of Pakistan" against foes like the Haqqani network blamed for attacks in Afghanistan, said Democratic Senator Jack Reed.

Reed said he had pressed top Pakistani officials to curtail the Haqqani network's operations in Afghanistan, notably its couriers, as well as other groups blamed for planting deadly roadside bombs targeting US forces.

"Action needs to be taken in days and weeks" said Udall, who said US intelligence agencies and their Pakistan counterparts have been working together but need to strengthen their cooperation.

"We'd like it to be stronger, we'd like it to be more disclosive, there have been some shortcomings, there have been some mixed signals, but all in all we continue to cooperate with them and they cooperate with us in many ways," he said.

Reed said Clinton's visit had "dramatically" improved Pakistani leaders' attitude towards US pleas for help, citing "renewed interest for the government of Pakistan to cooperate with us," but said he hoped for concrete actions.

"The words are right, the sentiment is right, but there has to be real steps going forward to help us," said Reed, a former US Army Ranger who sits on the Senate Armed Services Committee.

"They'll probably be invisible to most people but they have to be very real," said Reed.