A six-hour street party carnival is at the heart of a "revamped" programme for Edinburgh's forthcoming Hogmanay celebrations.

The 2018 programme is the first to be directed by entertainment company Underbelly, one of the largest events organisers at the capital's annual Fringe festival.

Bosses vowed the city's new year celebrations will be "refreshed, re-energized and better than ever before", as they unveiled their plans for the world-renowned event.

Under the festival's 25th birthday programme, the 60,000-capacity street party will begin at 7pm and last until 1am on New Year's Day.

Bands and DJs on stages, street performers, dancers, acrobats, flash mobs and fire eaters will all combine to bring a carnival-type spirit to Princes Street.

Actor and presenter Sanjeev Kohli, best-known for playing shopkeeper Navid in the BBC comedy Still Game, will host the street party, helping to entertain the crowds and guide them through the arena.

An extended fireworks display from the ramparts of Edinburgh Castle will see in the new year when the midnight hour strikes.

The three-day festival opens on December 30 with the traditional Torchlight Procession.

It will blaze a new path through the historic heart of the city this year, around Holyrood Palace and the Scottish Parliament towards Holyrood Park.

The event will also mark the beginning of 2018 as Scotland's Year of Young People, organisers said.

The following day, families will have the chance to celebrate new year together in West Princes Street Gardens at a new event entitled Bairns Afore.

The family-friendly celebration includes an hour of entertainment and ends with its very own "midnight" fireworks moment at 6pm, allowing families to take their children home before the late night fun gets under way.

On New Year's Day, people will get the chance to take part in the annual dive into the chilly Firth of Forth for the Loony Dook, raising money for a range of charities in the process.

At dusk, the Unesco city of literature will celebrate its literary heritage with projections across buildings and landmarks around the city.

Underbelly directors Charlie Wood and Ed Bartlam said: "We are humbled and thrilled to be delivering a new programme for Edinburgh's Hogmanay in 2018.

"Edinburgh can claim to be the home of new year festivals and we will work hard to ensure the programme delivers something fresh and exciting every year to keep residents, UK visitors and international tourists flocking to this world famous festival city through the winter months."

Winter Festivals Minister Alasdair Allan said: "Hogmanay hugely contributes to promoting Scotland as a fantastic visitor destination, a host of the world's major events and a dynamic country rich in culture and creativity.

"Most importantly, it enhances Scotland's reputation as a place where everyone is assured a warm welcome, whether they are visiting the country, are here for business or to study, or have chosen to live and work here."

The City of Edinburgh Council awarded the three-year contract for the Christmas and Hogmanay festivities to Underbelly earlier this year.

Unique Events had organised the city's official Hogmanay celebrations since they were established along with the local authority in 1993.

Tickets for a number of the events are on sale from Tuesday.