1) UK Government
http://www.uktradeinvest.gov.uk/
Look on the sector pages for any prioritisation of opportunities for UK companies which has already been carried out.
2) World Factbook
http://www.cia.gov/
The Central Intelligence Agency publish information about many characteristics of most countries – find the World Factbook in the Library & Reference section, then look at ‘Notes & Definitions’ for your chosen criteria across the world.
3) International Organisations
United Nations http://www.un.org/ plus UN agencies e.g. UNCTAD, ILO, UNESCO, UNICEF, etc)
European Union http://www.europa.eu.int/
http://mkaccdb.eu.int/ - search the Applied Tariffs Database to compare import duties by market (outside the European Union)
OECD http://www.oecd.org/
World Bank http://www.worldbank.org/
Intracen www.intracen.org/tradstat
A list of international organisations can be found at www.developmentgateway.org/DataStatistics
4) Nationmaster
http://www.nationmaster.com/ includes many statistics, but check out the source and date of the figures before using them.
5) Published Market Reports
http://www.marketresearch.com/
Here you may find a regional or global report on the industry or sector you are investigating. Registration is free. You many need to contact the publisher to help you to decide whether to buy the report. The Export Marketing Research Scheme (tel 024 7669 4484) may be able to part fund such a purchase. You must, however, secure agreement from the Scheme before buying the report.