Leaders of the group of 53 nations, mainly former British colonies, will meet in Trinidad and Tobago from Friday and one of the issues to be discussed is who will host the next summit in 2011.
Sri Lanka is one of a number of countries bidding to host the next summit, a British government sorce said.
"The Prime Minister (Gordon Brown) has real concerns about Sri Lanka's bid. We simply cannot be in a position where Sri Lanka, whose actions earlier this year had a huge impact on civilians," source said speaking on condition of anonymity.
"The Prime Minister will talk to other leaders about this, but is clear this won't wash," the source said.
Britain had criticised the conduct of the war earlier this year and remains concerned about the situation of about 130,000 displaced people in camps in Sri Lanka.