London Heathrow Airport served 5.8 million passengers in March 2014, down 2.8% from the corresponding period in 2013.
The number of seats per aircraft increased 1.9%, while load factors decreased 3.6 percentage points to 72.2%, compared to last year.
The decrease in number of passengers and load traffic can be attributed to the shift of Easter holidays into April this year, from March last year.
Among the emerging markets, passenger traffic to Mexico was up 19%, China was up 11.6% and Turkey was up 7.2%
The number of passengers per aircraft was up 1.1% to 139.6.
Heathrow CEO Colin Matthews said, "Passenger numbers were in line with expectations in March, consistent with the Easter bank holiday moving from March last year to April this year.
"Dubai's announcement that it has overtaken Heathrow in the last two months shows that the UK will soon no longer have the world's number one airport for international passenger traffic. We want Britain to continue to compete globally against the best hub airports in the world but without a third runway, Heathrow's comparative decline will make the whole of the UK less attractive to do business," Matthews said.
In July, Heathrow Airport will commence the deal with Colombia's national airline Avianca to provide the UK with its first direct connection to Colombia for nine years.
As part of the Star Alliance, Avianca's passengers will be offered four flights a week through Heathrow's new second terminal, which will open this June.
The airport also announced plans to introduce a new initiative to manage arriving flights based on the amount of time between the flights rather than distance.
The new system, recommended by the independent Airports Commission, will lower delays and cancellations due to the strong head winds caused as a result of arriving flights landing closer together.
Image: Heathrow Airport saw a decrease in number of passengers in March this year due to the shift of Easter holidays into April , from March last year. Photo: courtesy of Heathrow Airport.