UPDATE 1-U.S. Treasury Dept will allow 90-day wind-down period for fresh Iran sanctions

The U.S. Treasury Department said on Thursday it would allow for a 90-day period to wind down transactions in certain sectors of Iran's economy hit with fresh U.S. sanctions last week.

The period, which expires April 9, will allow transactions to be wound down in the construction, mining, manufacturing or textiles sectors of Iran's economy that could fall under the sanctions, though new business would still be sanctionable, according to the Treasury Department's website. The United States imposed more sanctions on Iran on Friday in retaliation for its missile attack on U.S. forces in Iraq last week and vowed to tighten the economic screws if Tehran continued "terrorist" acts or pursued a nuclear bomb.

The targets of the sanctions included Iran's manufacturing, mining and textile sectors as well as senior Iranian officials who Washington said were involved in the Jan. 8 attack on military bases housing U.S. troops.