Tighter international trade restrictions on Russia could trigger a flood of wheat onto global markets.

Ukraine and Russia, along with North America, are Australia's biggest grain export competitors.

Market analysts are expecting Russian wheat yields to reach 50 million tonnes this year, with 20 million tonnes set for export.

Harvest of that grain is currently underway at a time when the United States and the European Union are considering further sanctions on Russia following the Malaysian Airlines plane crash.

Sydney University economics lecturer Mark Melatos says Russian wheat exporters might flood the market if they fear sanctions will restrict their exports.

"At the moment, it looks like the summer crop in Russia and Ukraine is going to be huge," he said.

"They're going to have a lot of grain sitting around and they may need to get rid of it, especially if they're trying to beat some trade sanctions that they think might be coming.

"That could really forces prices down across the board."

Sanctions are restrictions on economic activity, typically between two or more countries.

Dr Melatos says sanctions usually occur in two forms - as trade barriers or restrictions on financial transactions between the two countries.

He says the US expended its sanctions on Russian individuals with close ties to the Kremlin, banks and businesses just days before the Malaysian Airlines crash.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 7 minutes 4 seconds 7 m Economics lecturer Dr Mark Melatos on the impact of US and EU sanctions on Russia and global wheat markets ( Brett Worthington ) Download 3.2 MB

"Sanctions could be very damaging on both sides," Dr Melatos said.

"On the Russian side, the costs are obvious.

"Their exports, or if they were financial sanctions, the costs to their businesses and banks would be very large and easy to see if they weren't able to transact business on a global scale.

"The cost to the imposing countries come from a number of directions.

"Firstly, someone buys the exports that Russia sells [and] those countries won't be able to buy exports any longer. So, for example, if they are buying Russian gas or if they are buying Russian wheat, they're going to have to find alternative suppliers.

"If we assume they were importing these things from Russia because they were priced well, they're going to face increased costs because they are going to be buying these products from new suppliers who are probably more expensive."

Dr Melatos says stricter sanctions are likely to hit gas and financial transactions the hardest.

He says wheat prices could increase if sanctions led to a complete trade embargo between Europe, the United States and Russia.

"If the sanctions meant the wheat couldn't be traded, then there would be less wheat supplied on the world market so prices would rise," Dr Melatos said.

"This would be great news for Australia and other big wheat exporters.

"There would be more demand for their product and they would be able to get higher prices."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 4 minutes 48 seconds 4 m 48 s Commodities analyst Hannah Janson on the impact of Russian trade restrictions on wheat exports ( Brett Worthington ) Download 2.2 MB

Australia exports about half of its grain yields to northern Africa, the Middle East and South East Asia.

Australia produced about 27 million tonnes of wheat in 2013 and is forecast to yield about 25 million tonnes in 2014.

Russia's 2013 wheat yield was about 50 million tonnes and it exported 20 million tonnes.

Ukraine is the world's fifth largest wheat exporter.

The Odessa region in Ukraine exports about six million tonnes of grain, about half of the country's total grain exports, each year.

The Crimea region, which Ukraine and Russia fought over earlier this year, used to export about 5 per cent of Ukraine's grain exports.

In May, tension between Russia and Ukraine led to riots in the Odessa region leading to the deaths of more than 40 people.

The riots triggered fears the region could lose access to its ports and restrict exports of grain.

The tension between Russia and Ukraine prompted a spike prices, with wheat selling for around A$300 a tonne.

"We had this geo-political factor, but there was also a lot of uncertainty around the shape of the US winter wheat crop and how much wheat was actually going to come out of drought-stricken areas in the southern plains," said Hanna Janson, a commodities analyst with Profarmer.

"So as much as the rally seemed to be led by the Ukrainian-Russian conflict, it was exacerbated by this fundamental concern as to whether or not they'd actually be enough global wheat this season."

In the month since, wheat has traded around A$220 a tonne, with the Malaysian Airlines crash sparking just a A$5 per tonne rise.

That increase was wiped away the next day and prices have remained relatively flat in the days since.

Countries have continued to buy Russia's grain on the expectation that they will be able to access it.

"As much as the market was spooked with a flashback to the March rally and the situation when conflict in Russia and Ukraine first started to evolve, they've mulled that over and it is difficult for them to get a handle on what sanctions might actually mean and whether or not they're likely to impact on food exports," Ms Janson said.

"As a result, we've seen the trade put that to the back of their mind for a while and go back to trading on the fundamental factors."

Ms Janson says she expects a trade embargo or a political uprising in Russia will be needed for markets stop buying grain from the region.

She says as the harvest continues throughout Russia, yield forecasts are continuing to increase.

"The reality is there's still going to be a really large crop in that Black Sea region," Ms Janson said.

"There's still going to be quite a lot of wheat possibly able to hit the market over the coming season."