PARIS/HAMBURG, May 22 (Reuters) - European wheat traded slightly lower on Friday but was on course for a second consecutive weekly gain, with prices supported by a weaker euro that improved export prospects.

Benchmark September milling wheat BL2U6 on Paris-based Euronext was down 0.5% by 1430 GMT to €215.25 a metric ton.

The dollar held near six-week highs as traders weighed the prospects of a near-term deal to end the Iran war and assessed whether the U.S. Federal Reserve would raise interest rates if inflation continued to accelerate. FRX/

"The weak euro gives hope that more EU export sales will be possible," a German trader said.

Operators were awaiting confirmation of talk that French, German, Polish and Russian wheat has been sold to Mexico, an unusual customer for EU wheat.

"This is right in the back yard of U.S. exporters but confirmation of actual sales is still needed,” the trader said.

German wheat exports to major importer Indonesia will be possible from June after a plant safety (phytosanitary) agreement between the two countries, two industry associations said on Friday.

Traders said this raised good prospects for sales of both German milling wheat and feed wheat.

In overall thin export demand, an Indonesian buyer was on Friday seeking a panamax load of 11.5% wheat from the Black Sea region at around $278 a ton cost and freight included (c&f) for August/September shipment and a Vietnamese buyer was seeking a panamax load of Black Sea wheat at about $260 a ton c&f for July/August shipment.

But bearish news being debated included forecasts of a good crop in Turkey, recently a big importer, and Argentina cutting wheat export taxes.

Meanwhile, widespread rain in May means German wheat is in a good state for this time of the season, raising prospects for a decent harvest this summer.

In France, crop ratings remained stable and above last year, which traders viewed as encouraging as the country braces for a severe heatwave.