WASHINGTON (Reuters) - Average interest rates on U.S. 30- and 15-year mortgages rose in the latest week after dipping to new record lows as the Iraqi conflict led to a rise in bond market yields, Freddie Mac said on Thursday.

Rates on 30-year mortgage rose to an average 5.79 percent in the week from a record low of 5.61 percent last week, while 15-year mortgages shot upward to an average 5.11 percent from last week's record low of 4.93 percent, it said.

One-year adjustable rate mortgages rose to an average 3.75 percent from the record low 3.68 percent the previous week.

Freddie Mac began tracking 30-year mortgages in 1971, 15-year mortgages in 1991 and the ARM in 1984.

"Lack of uncertainty around the Iraq conflict caused bond market yields to reverse their downward spiral of recent weeks and mortgage rates followed in tandem," Frank Nothaft, Freddie Mac chief economist, said in a statement.

"But there are other uncertainties about the length of the conflict and its impact on the economy that will influence mortgage rates in the weeks to come, so this rise in rates may be only temporary," Nothaft added.

On Tuesday the Commerce Department said U.S. February housing starts plunged 11.0 percent -- the largest drop since January 1994 -- to an annual rate of 1.622 million units.

Next week the National Association of Realtors will release February existing home sales while the Commerce Department issues new home sales data for last month.