GRAINS-Chicago oilseed and grain futures wobble over Iran war uncertainty

BEIJING, March 27 (Reuters) - Chicago oilseed and grain futures fluctuated between gains and losses on Friday, as investors monitored developments in the Middle East amid mixed signals from the U.S. and Iran about efforts to end the war.

The most-active corn contract on the Chicago Board of Trade (CBOT) Cv1 gained 0.1% to $4.67-1/2 a bushel, and was up 0.4% so far this week.

CBOT wheat Wv1 lost 0.1% to $6.04-1/2 a bushel, but was up 1.6% so far this week. Soybeans Sv1 gained 0.1% to $11.74-1/2 a bushel, taking the weekly gain so far to 1.1%.

Corn and soybeans usually track movements in oil prices as they are widely used for biofuel feedstock.

Oil prices fell in early trade and were down over a volatile week after U.S. President Donald Trump said talks with Iran to end the war were going "very well" and that he would pause attacks on the country's energy plants for 10 days.O/R

Despite Trump's upbeat assessment, an Iranian official said the U.S. proposal to end the war was "one-sided and unfair."

Iran continued to retaliate against U.S. and Israeli strikes by hitting Israel and U.S. bases. It also struck Gulf states and effectively blocked Middle East fuel exports via the Strait of Hormuz, which carries about 20% of global oil and liquefied natural gas. Iran has said it is not engaged in talks with Washington.

Traders are also awaiting a possible announcement of revised U.S. biofuel targets at a White House event later in the day.

Next week, market attention will be on the U.S. Department of Agriculture's acreage estimates, due out on Tuesday, with rising fertiliser and fuel prices due to the Middle East war heightening interest in farmers' planting decisions.

On Tuesday, Russia, which controls up to 40% of the global trade in ammonium nitrate, said it will suspend exports of the fertiliser until April 21 to ensure sufficient supply during the spring planting season.