UPDATE 2-Iran could ban EU oil exports next week -lawmakers

* Parliament to vote on EU oil ban Sunday

* Aims to deny EU 6-month phase-in of embargo

* EU agreed on Monday to ban Iran oil imports from July 1

* Populist move could cause glut, may force Iran to discount (Adds EU reaction, analyst comment, Friday prayers, oil price impact)

By Hashem Kalantari and Robin Pomeroy

TEHRAN, Jan 27 (Reuters) - A law to be debated in Iran's parliament on Sunday may halt oil exports to the European Union as early as next week, foiling an EU plan to phase in an oil embargo gradually to help its struggling economies adapt, lawmakers said on Friday.

"On Sunday, parliament will have to approve a 'double emergency' bill calling for a halt in the export of Iranian oil to Europe starting next week," Hossein Ibrahimi, vice-chairman of parliament's national security and foreign policy committee, was quoted as saying by the semi-official Fars news agency.

Parliament is pushing for the export ban to deny the EU a six-month phase-in of the embargo on Iran's oil, which the bloc agreed on Monday as part of a raft of tough new Western sanctions aimed at forcing Iran to curb its nuclear programme.

The EU accounted for 18 percent of Iranian crude oil sales in the first half of 2011, according to the U.S. Energy Information Administration (EIA), making it Iran's second-biggest customer after China.