SYDNEY, Aug. 8 -- Australian Prime Minister Tony Abbott said on Friday that Australia would enforce tougher sanctions against Moscow if Russian troops crossed the Ukraine border.

Abbott made the comments after Russia on Thursday imposed a ban on food imports from countries including Australia, after Western nations applied sanctions against Russia over Ukraine.

Abbott told reporters in Sydney that if Russian President Vladimir Putin allowed his troops to cross the border into the Ukraine,"you will find increased sanctions by Australia".

"We will be working towards strong sanctions. The way to avoid increased sanctions is for Russia to call off what it appears to be in preparation for."

Abbott said now that Australian personnel have left the Malaysia Airlines crash site in Ukraine, tougher sanctions against Russia were now a viable option.

"I didn't want to change the level of our sanctions while we had a personnel on the ground within 20 or 30 kilometres of the Russian border but now that our personnel have withdrawn from the site, now that our personnel are in the process of returning to the Netherlands after largely completing Operation Bring Them Home certainly you will find increased sanctions by Australia."

Australian farmers will suffer as a result of Russia's one-year ban on agricultural products from Australia, the European Union, the United States, Canada and others.

"I don't want to minimize this issue obviously because we do do hundreds of millions of dollars of agricultural business every year with Russia," Abbott said.

Abbott said if Russia wanted to avoid increased sanctions it must stop interfering in the affairs of Ukraine and supporting the separatists.

"If there is any movement by Russian forces across the border, it won't be a humanitarian mission, it will be an invasion," he said.