A top US lawmaker has described Pakistan as America's ugliest ally, as on the one hand Islamabad proclaims to be a friend of Washington, but on the other, backs terrorists and terrorism.

In an opinion piece titled 'Pakistan's Long History of Duplicity' that has been published in the Washington Times, Senator Ted Poe, a Republican who represents Texas's 2nd Congressional District in the US House of Representatives, said Pakistan must be held accountable for continuously working against the interests of the United States.

He said there are three kinds of allies that the United States has -- the 'good', the 'bad' and the 'ugly'.

Poe said the good allies are the ones who share common interests and values with America. The bad ones are those who often sponsor terrorism, undermine America's goals, and flaunt their disdain of the United States, and the ugly are countries like Pakistan who take billions of dollars in aid from the United States and simultaneously back the terrorists responsible for killing Americans worldwide.

He describes countries like Pakistan historically as a "Benedict Arnold". Benedict Arnold was a general during the American Revolutionary War of the 1770's who originally fought for the American Continental Army, but later defected to the British Army.