Heathrow is to counter criticism over a lack of domestic connections by unveiling plans for more regional routes if it is allowed to expand.
The airport will pledge to boost connections to areas not currently served by internal flights.
At least six more routes would be created, including to Liverpool, Humberside, the Isle of Man, Jersey and Newquay.
Heathrow currently serves Aberdeen, Belfast City, Edinburgh, Glasgow, Inverness, Leeds/Bradford, Newcastle and Manchester.
A document to be released today says improvements to bus and rail connections will put 70% of the UK’s population within three hours of Heathrow.
It follows criticism of the airport, which has cut the number of domestic flights over the past decade.
Today’s pledges form part of a new charm offensive designed to win support from outside the south-east for a third runway, The Times reported.
Heathrow is battling with Gatwick, which is bidding for a second runway and started its own campaign tour in Manchester last week.
A final decision on airport expansion is hoped to be made during the four weeks between the EU referendum on June 23 and the start of the summer parliamentary recess on July 21.