BAA, which owns Heathrow Airport, made the following statement:
"Immigration waiting times during peak periods at Heathrow recently have been unacceptable and we have called on the Home Office to address the problem as a matter of urgency.
"There isn't a trade-off between strong border security and a good passenger experience - the Home Office should be delivering both."
Long queues had formed at passport control on Thursday and Friday.
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The 47-year-old man died shortly after 3pm on Tuesday.
Specialist explosive detection dogs searched through the town examining letter boxes and phone booths for signs of potential devices.
Temperatures reached 29.1C in St James's Park, central London.