The day of the Royal wedding between Prince William and Kate Middleton will be a public holiday, Prime Minister David Cameron announced today.

The extra day off on April 29 means that millions of workers will enjoy two long weekends in quick succession, with just a three-day working week in between.

Cabinet agreed the bank holiday for England, Wales and Northern Ireland at its regular weekly meeting in 10 Downing Street this morning.

Scotland is widely expected to follow suit. First Minister Alex Salmond said his cabinet would discuss the issue later today and make an announcement "as quickly as possible".

There was speculation at Westminster that the timing of the wedding may have an impact on the referendum on the Alternative Vote system for Westminster elections, due to take place on May 5, the same day as elections to English councils and devolved legislatures in Scotland, Wales and Northern Ireland.

Some campaigners are understood to be concerned that it may be more difficult to engage voters in the arguments around electoral reform at a time when the media will inevitably be focusing on the royal nuptials.

A royal source confirmed that Prime Minister David Cameron was consulted on the issue and was "very content with the selection of the date".

Announcing the holiday, Mr Cameron said: "The wedding of Kate and William will be a happy and momentous occasion. We want to mark the day as one of national celebration.

"A public holiday will ensure the most people possible will have a chance to celebrate on the day."

Mr Salmond extended his "warmest congratulations" to the royal couple "as they look forward to a wonderful wedding day and the beginning of a long and very happy marriage".

But he added: "The wedding day will take place during the Scottish election period, which has implications for the electoral and parliamentary timetable, and we will work through these in close consultation with the Holyrood authorities."

The wedding comes hot on the heels of the four-day Easter weekend, stretching from April 22-25 and taking in bank holidays on Good Friday and Easter Monday.

Then after just three days back at work there will be another four-day weekend from April 29 to May 2 taking in the Royal wedding and the May Day bank holiday Monday.

Richard Calvert, managing director of Thomas Cook holidays, welcomed it as "great news for savvy travellers" who might take the opportunity to leave the country for early summer sunshine in Turkey, Egypt or the Canaries.

"Holidaymakers now only need to take five days annual leave to benefit from a 14-night holiday," said Mr Calvert.

The TUC called for the extra bank holiday to be made permanent.

"Working people will look forward to the extra bank holiday next year to celebrate the royal wedding," said a TUC spokesman. "The UK would benefit from having more days of national celebration.

"With a further bank holiday to come in 2012 for the Queen's Diamond Jubilee, people will get used to the extra day off so we should make it a permanent fixture, with a new community day bank holiday from 2013 onwards."

But the pressure group Republic, which campaigns for an elected head of state, said it was "absurd that the whole country gets a day off for something most people are not interested in".

"At least 20% of the population are opposed to the monarchy, many more simply don't care about it," said spokesman Graham Smith.

"Polls, newspaper sales and complaints to the BBC are all showing a country that simply isn't excited about the wedding.