President Barack Obama has said that the US government has let down the families of Americans held hostage by armed groups abroad, and outlined new policies that could make it easier for those families to pay ransom to help free their loved ones.

"These families have already suffered enough and they should never feel ignored or victimised by their own government," Obama said on Wednesday as he detailed the results of a six-month review of US hostage policy.

The review's conclusions aim to streamline and improve communications with families, who have sharply criticised the government for providing them with confusing and contradictory information. Some families have complained about threats of criminal prosecution if they seek to pay ransom - threats Obama said would end.

"The last thing we should ever do is add to a family's pain with threats like that," Obama said.

30 hostages

More than 30 American are currently being held hostage outside the US, Obama's homeland security and counterterrorism adviser Lisa Monaco said.

The president's pledge essentially clears the way for families to take actions the US government has long said put Americans abroad at greater risk. While no formal changes were being made to a law prohibiting material support for groups deemed as terrorists, the justice department indicated it would essentially ignore the law in most situations involving families.

We really feel that our government needs to have a clearer policy and be more upfront about what they can and cannot do, or will and will not do. Diane Foley, mother of slain hostage

Obama expressed concern that paying ransoms makes Americans greater targets for kidnapping and increases funding for terrorists. He also said the US government would continue to abide by the "no concessions" policy, but made clear that government officials can have contact with hostage-takers.

Critics of the White House review argue that allowing families to do what the government will not, could lead to those same troubling consequences.

"We have had a policy in the United States for over 200 years of not paying ransom and not negotiating with terrorists," said John Boehner, a senior Republican Congressman. "The concern that I have is that by lifting that long-held principle you could be endangering more Americans here and overseas."

The president spoke shortly after meeting privately with several hostages' families and some former hostages. While more than 80 Americans have been taken hostage since the 9/11 attacks, the issue has gained fresh attention in recent months following the deaths of several Americans held by the Islamic State of Iraq and the Levant (ISIL) group, al-Qaeda and others.

"We really feel that our government needs to have a clearer policy and be more upfront about what they can and cannot do, or will and will not do," said Diane Foley, mother of journalist James Foley who was beheaded by ISIL last year. "We felt like we were in the dark a lot."

Despite the ban on the US government making concessions to alleged terrorists, the Obama administration did negotiate with the Taliban last year to win the release of Army Sergeant Bowe Bergdahl, who was captured after walking away from this post in Afghanistan. Five Guantanamo Bay detainees were exchanged as a condition of his release.

White House officials say those negotiations were permissible because Obama sees a special responsibility to leave no American service member behind on the battlefield. Some hostages' relatives have argued against the government making such distinctions between US citizens.

In a step aimed at streamlining communications with families, the White House also announced the creation of a "Hostage Recovery Fusion Cell" that will coordinate recovery efforts among various government agencies.