The Edinburgh Festival Fringe is getting so big it could reach nearly as far as Falkirk and the furthest edges of the EH postcode, its chief executive has revealed.

This year's Edinburgh Festival Fringe, which is the biggest yet with nearly 4,400 shows, will this year reach as far south as Innerleithen and also including events in Musselburgh, Dalkeith and Inveresk in East Lothian.

The organisers of the Fringe, which celebrates its 70th year in 2017, said the expansion is part of a conscious effort to include events within the large EH postcode, which feasibly could include shows staged as far from the Old Town as Bo'ness near Falkirk, Bathgate, Peebles, South Queensferry, Dunbar and North Berwick.

The organisers of the Fringe, which has in its history staged events in the Carnegie Hall in Dunfermline, Fife, and on Inchcolm Island in the Firth of Forth, said as long as shows are based in the broad EH postcode area, they can be part of the Fringe - if shows from further afield wish to apply, they would also be considered.

Unveiling this year's programme, in which the number of shows has risen by 3.9% to 3,398, with 300 venues, Shona McCarthy, chief executive of the Edinburgh Festival Fringe Society, said: "I think it's one of the exciting developments of the festival this year, and it is partly to do with the access and outreach programme we have invested in in that last year or so.

"We have reached out to make connections on the outskirts of the city, from edge to the centre, and we have been doing roadshows across Scotland to raise awareness. I think it's great."

She added: "We don't dictate - if people in East Lothian want to put on Fringe shows and register with the Fringe, they can.

"This year we have much more active engagement from Leith, which is also exciting, and the programme has a separate map of Leith and a ticket depot in Leith."

A spokeswoman added: "The EH postcode gives us the geographic range [of the Fringe], but actually if it were to come up, we would have a conversation about what that means to the festival.

"When we have had things on islands in the Forth, meeting points have been within the EH boundary, so it has always had that geographical range - but if someone came to us and said 'we want to do this', we would have a conversation."

This year two performances of Oceanallover’s dance piece Sea Hames will take place at Dalkeith Country Park, and The Brunton presents a programme of music and theatre including The Mikado at Musselburgh Race Course.

Alice Through The Looking Glass will be staged in the surrounds of Inveresk Lodge Garden, and Beyond Borders Festival Scotland brings a programme of debate, discussion, art and music to Traquair House in Innerleithen.

This year the Fringe will feature theatrical performances for the first time at Hibs Easter Road ground, a clutch of shows will be staged outside the city, while one opera will be staged in a toilet.

Ms McCarthy also said that the security of the Fringe was a key concern this year, particularly after the terrorist attack on the MEN Arena venue in Manchester.

"Security is uppermost in everybody's mind," she said, and said that she was constantly in contact with Police Scotland, counter-terrorism and the city council over security, with updated plans in place.

However, each venue is responsible for specific measures - such as bag-checking or metal detectors - and she said it was unlikely that large public events such as the performances on the Royal Mile would have bag checks.

She said: "We don't have control over individual venues, some venues may choose of their own volition to do bag checks, and we are still in talks with police to decide what we will do in terms of the areas we are responsible for.

"With the High Street and the Mound, these are open, public areas so it is not feasible, possible or even desirable to do bag checks in public spaces, but you may see some venues who will do that."

A spokeswoman added: "It would be wrong of us to comment on what the advice is, until we are closer to the event. There is no specific threat to Edinburgh, to Scotland, than we have ever been. That is the message we would give to the public."

Nik Whybrew, the operations director at the Assembly venues, said: "We have a robust and detailed plan in place for all Assembly venues, which has been developed over the last five years and is reviewed every year.

"As usual in conjunction with Police Scotland and the local authority we will review current plans and update them where necessary."

The Pleasance venue said, in a statement: "Public safety has always been our top priority.

"We have been and will continue to work closely with University of Edinburgh, Edinburgh University Students’ Association, City of Edinburgh Council and with advice from Police Scotland to review our security procedures."

In a percentage breakdown of the programme, comedy is up 1% to 35% of the total, music is down to 14% from 15%, there is more theatre by 1% (28%) and there are 686 free shows, up nearly 7%, 215 'pay as you want' shows, up nearly a third, but 2.8% less premieres - 1,683.

This year’s programme features theatre, dance, circus, physical theatre, comedy, music, musicals, opera, cabaret and variety, children’s shows, free shows, exhibitions, events and spoken word.

There are some changes to the venues at the festival, with Hibernian Football Club is to be a venue for the first time, for Strange Town’s production of A Field of Our Own.

The Leith Volcano, formerly St James Church on Constitution Street, will be flooded for Volcano Theatre’s production of Chekhov’s The Seagull.

Army At the Fringe will see the Army Reserve Centre on East Claremont Street transformed into a venue, while Gilded Balloon at Rose Theatre will feature four performance spaces in the in the old Charlotte Chapel on Rose Street.

Sweet Holyrood features three performance spaces in the Macdonald Holyrood Hotel while C royale is a new C venues hub on George Street, occupying the Royal Society of Edinburgh and presenting a mix of new writing, cabaret, circus and comedy.

SpaceUK also return to theSpace on North Bridge after a two year hiatus, while Venue150 at EICC expands in to the tunnel below the main venue where Trainspotting Live will take place.

New free venues for 2017 include Black Market on Market Street which features six performance spaces in the former offices of the Royal Edinburgh Military Tattoo, while in the Grassmarket, 52 canoes will host shows in its basement lounge.

More unusual locations for Fringe shows this year include the Lochrin Belle boat which will host Scotch Egg Club Presents: Whisky on Water , a food and drink cruise along Edinburgh’s Union Canal.

Novotel Swimming Pool becomes a venue for 274 Theatre’s water-based production Brodsky Station and Chamber Pot Opera brings 'toilet based opera' to The Bathroom at Assembly Hall.