Chinese and Russian firms are the most likely to pay bribes while operating abroad, and the most corrupt sectors are public works contracts and construction, according to Transparency International?s latest ?Bribe Payers? index?. India?s score has improved the most in a global index, the rights group said.

China and Russia rank bottom, in 27th and 28th place respectively, in the 2011 index released on Wednesday, while the Dutch, Swiss, Belgians, Germans and Japanese get the top scores. Britain and the United States rank eighth and ninth. But the Berlin-based anti-corruption campaigners said not one of the 28 countries surveyed ? which include all of the G20 ? was perceived as ?wholly clean of bribery? and few had made a major improvement since the last bribery index in 2008.

?India?s score improved the most, with an increase of 0.7, but it still remains near the bottom of the table. Canada and the United Kingdom saw the most significant deterioration in their scores with a drop of -0.3,? read the report.

Despite the improvement, India continues to be ranked near the bottom of the global Bribe Payers Index ? 19th in a list of 28 countries ? as there was a high likelihood of Indian companies paying bribes abroad.

The group asked 3,016 business executives in 30 countries ? selected by the value of their foreign direct investments and exports, plus their regional significance ? how often companies based in countries in the survey engaged in bribery.

Transparency urged countries to ratify conventions against bribery under the auspices of the United Nations, the Organisation for Economic Cooperation and Development and the European Union. ?In their meeting in Cannes this week, G20 governments must tackle foreign bribery as a matter of urgency,? said Huguette Labelle of Transparency International. ?It is of particular concern that China and Russia are at the bottom of the index.?

It added that the leaders of G-20 nations, during their meeting at Cannes, were expected to recognise the steps taken by countries like India to tackle foreign bribery.