Department for Transport, provides information relating to all forms of transport within the UK.  Areas of special interest to importers and exporters may include the sections on aviation, ocean and channel tunnel security.
http://www.dft.gov.uk/


The Market Access Database is a free, interactive, easy to use service providing information about Market Access conditions in non-EU countries.
http://mkaccdb.eu.int


HM Revenue & Customs web site provides a vast array of useful information on importing and exporting.
http://www.hmrc.gov.uk


The International Civil Aviation Organisation’s (ICAO) chief activity is standardisation, the establishment of International Standards, Recommended Practices and Procedures covering the technical fields of aviation as well as the safe transport of dangerous goods.
http://www.icao.int


The Foreign and Commonwealth Office (FCO) offers advice on countries as well as providing a variety of business services for UK firms who want to trade and export in overseas markets. 
http://www.fco.gov.uk/


The International Air Transport Association’s (IATA) 'DG Centre of Expertise' strives to lead industry efforts to ensure the safe handling of dangerous goods in air transport, by providing a broad array of technical knowledge, products, services and training solutions tailored to meet industry needs:
http://www.iata.org/whatwedo/cargo/dangerous_goods