WASHINGTON: Congress ratcheted up the pressure on the Obama administration to slap the terrorist label on the Haqqani network, the militant group responsible for plotting and launching attacks from Pakistan against US-led forces in Afghanistan.

By voice vote, the Senate approved a bill on Thursday that would require the secretary of state to report to Congress on whether the Haqqani network meets the criteria to be designated a foreign terrorist organisation and if not, to explain why.

The report is due within 30 days of the president signing the measure.

The bill now goes to Obama.    The administration has sanctioned top individuals of the Haqqani network, but it is still reviewing whether to label the entire organisation. That delay has frustrated members of Congress.

Rep. Mike Rogers, Republican chairman of the Intelligence Committee, had added an amendment to the bill stating that it was the sense of Congress that the Haqqani network meets the definition of a terrorist organization and they should be designated as one.

The State Department has defended its effort, citing its sanctions of the network's top individuals.

The Haqqani network, largely operating in eastern Afghanistan and northwestern Pakistan, is affiliated with both the Taliban and al Qaeda. US officials say it represents one of the biggest threats to Afghanistan stability because it is believed to use Pakistan as a rear base for attacks on American and coalition troops in Afghanistan.

The congressional votes come just weeks after the United States and Pakistan ended a rancorous seven-month standoff with Secretary of State Hillary Rodham Clinton apologising to Pakistan for the killing of 24 Pakistani troops last fall and in return securing the reopening of critical Nato supply lines into Afghanistan.

Throughout the uneasy relationship between the United States and Pakistan, American officials have pressed Islamabad to crack down on the extremist Haqqani network.

The bill states that ''nothing in this act may be construed to infringe upon the sovereignty of Pakistan to combat militant or terrorist groups operating inside its boundaries.''    In May, the Republican and Democratic leaders of the House and Senate Intelligence committees wrote to Clinton asking her to act immediately in labeling the Haqqani network a terrorist group.

The four leaders said that based on meetings with US and Afghan officials in Afghanistan, ''it was clear that the Haqqani network continues to launch sensational and indiscriminate attacks against US interests in Afghanistan and the group poses a continuing threat to innocent men, women and children in the region.'' The four noted that it had been six months since the State Department had undertaken its ''final formal review'' of the Haqqani network.

''The Haqqanis have continued to attack US troops and the US embassy in Kabul during that period,'' the lawmakers said.

The letter also noted that the Obama administration may have been reluctant to act while Marc Grossman, the special representative for Afghanistan and Pakistan, was trying to negotiate a reconciliation agreement with the Taliban that may have included or affected the Haqqani network.