Washington: US lawmakers slammed "disgraceful" Turkey on Wednesday over its ties to Iran and charged Ankara had the "blood" of nine Turks killed in an Israeli raid on a Gaza-bound aid ship on its hands.

"There will be a cost if Turkey stays on its present heading of growing closer to Iran and more antagonistic to the state of Israel," warned Representative Mike Pence, the number three House Republican.

The group, firing an unusually harsh rhetorical broadside at a NATO ally, rebuked Turkey for backing the aid flotilla, criticising Israel, and opposing US efforts to impose new sanctions on Tehran over its suspect nuclear program.

"Because Turkey is a NATO ally, it's even more disgraceful, their actions," said Democratic Representative Eliot Engel, who joined his colleagues in accusing Ankara of drifting away from the West and into the arms of Iran.

"If we look at what the Turkish government has done in the past couple of years: they certainly have a very strong Islamic bent, but a bent in terms of looking towards Iran, and looking towards the Middle East, and not looking at the West and NATO anymore," said Engel.

The lawmakers slammed Turkey for backing an aid flotilla for Gaza and said Ankara was to blame for the deaths of eight Turks and a dual Turkish-US national in a May 31 raid on one of the ships, the Turkish ferry Mavi Marmara.

"I believe that blood is on the hands of Turkey," Republican Representative Peter King.

"As far as I'm concerned, Turkey is responsible for the nine deaths aboard that ship, it is not Israel's troops that are responsible," said Democratic Representative Shelley Berkley.

Pence said he would consider dropping his opposition to a US Congress resolution branding the World War I era mass killings of Armenians by Ottoman forces as "genocide" and hinted at other consequences.

Berkley said she had turned Turkish officials away from her office this week and would continue to do so "until I see and change in policy" and vowed to fight against Turkey's accession to the European Union.

"They don't deserve to be a part of the EU until they start behaving more like the European nations and a whole lot less like Iran," she said.