World Bulletin / News Desk 

British Prime Minister David Cameron said Europe had to stay united to keep sanctions on Russia in place despite any pain they caused the 28-nation bloc, urging the Group of Seven industrial nations to send Moscow a tough message on Ukraine.

Cameron was speaking after U.S. President Barack Obama said the meeting of the G7 in the Bavarian Alps would discuss standing up to Russian aggression in Ukraine, amid an upsurge in violence there that monitors have blamed on Moscow-backed separatists.

"We need to make sure Europe remains united," Cameron told reporters after arriving at the summit.

"It (sanctions) has an impact on all countries in terms of putting sanctions on another country. (But) Britain hasn't let our pre-eminence in financial services get in the way of taking a robust response to Russian-backed aggression and I don't think other countries should either."

British officials said separately that some unnamed east European countries had been raising concerns about the impact on their agricultural sectors stemming from the Russian sanctions. London felt all EU states had to endure the pain to ensure the sanctions remained in place, they said.

"On Ukraine I'm hoping for a good outcome where we can make sure that the sanctions are rolled over at the next European summit to show a united front against Russian-backed aggression," said Cameron.