Health chiefs are stepping up checks on mosquitoes and ticks living in and entering Britain.
Asian tiger mosquitoes can spread potentially fatal diseases
Experts suspect that Asian Tiger mosquitoes have already entered Britain on container ships docking in ports.
These mosquitoes are known to carry a number of serious and potentially fatal diseases.
While there is no evidence to suggest they infected any individuals, their discovery has concerned health officials.
The Health Protection Agency is working with staff at Heathrow Airport to ensure containers and luggage from at risk countries are checked.
Asian tiger mosquitoes, which get their name from their bright white markings on a dark background, are normally found in southeast Asia, parts of Africa and Central and South America.
However, there is concern that world climate change could see them arrive and survive in Britain.
Asian tiger mosquitoes breed much more easily than other types of mosquitoes.
Those recently discovered in Britain were found living in small pools of water in used motor vehicle tyres.
The concern is that these mosquitoes could have been carrying dengue fever or certain types of encephalitis virus.
Dengue fever can result in severe flu-like symptoms. One strain causes internal bleeding and can be fatal if not treated.
Encephalitis viruses attack the brain and
can also be fatal.
The HPA is also trying to map other breeds of mosquitoes and ticks in Britain.
They believe this will help them to predict any future outbreaks of diseases, like malaria and Lyme disease.
Dr Pat Troop, chief executive of the Health Protection Agency, said: "We are monitoring for these ticks and mosquitoes.
"We need to know which ticks and mosquitoes are surviving here and where they are."
The HPA is also launching an investigation into chemicals found in the environment amid concerns about their impact on people's health.
In its five-year corporate plan, published on Tuesday, it said the review will look particularly at the impact of chemicals on children.
"They are especially vulnerable to infections, poisons and chemicals and physical hazards in air, water and soil," the report states.
"Their development, health and well-being could be threatened by unsafe food and chemicals in household products and consumer goods."
The document points out that an estimated 600 new chemicals enter the market each month, on top of the 11 million already known and 70,000 in regular use.
Studies have claimed that exposure to some chemicals can have serious
effects on health, including the risk of birth defects and chronic diseases.
The HPA will also investigate public concern about the possible effects of long-term exposure to chemicals, such as those emitted from landfills, incinerators and industrial sites.
Dr Troop said: "We are not saying there is a problem. We are saying we are looking carefully to see if there is a problem or there isn't a problem.
"The public is concerned about many of these issues and it is important that we don't ignore it if there is a problem."