UK Prime Minister Rishi Sunak's decision to call an early general election means his flagship smoking ban will not pass before the current parliamentary session is suspended on Friday.

The Conservative party leader had pledged to create a "smoke-free generation" by introducing a law preventing young people from ever being able to buy cigarettes legally.

But the proposal, which had been seen as Sunak's legacy if he loses the election, was not included in the "wash-up" period where legislation is rushed through before parliament shuts down.

"Of course (I'm) disappointed not to be able to get that through at the end of the session, given the time available," Sunak told reporters during a campaign visit to Northern Ireland.

The bill was set to make it illegal to sell tobacco products to anyone born after January 1, 2009 -- effectively raising the smoking age by a year each year until it applies to the whole population.

"I stepped up to do something that is bold, that will make an enormous difference in the future of our country," added Sunak, who would be expected to reintroduce the legislation if he wins the nationwide vote.

Sunak, prime minister since October 2022, confirmed in a rain-soaked speech outside Downing Street on Wednesday that the UK would go to the polls on July 4 -- six months earlier than it has to.

The announcement means a number of his government's headline proposals are unlikely to see the light of day during this parliamentary term.

A bill making it more difficult for landlords to evict tenants looked set to be dropped, as did plans for a new football regulator.

Legislation designed to tighten venue security after the 2017 Manchester Arena attack in which 22 people died was also not due to pass in time.

Sunak, 44, conceded on Thursday that his controversial plan to forcibly remove the first failed asylum seekers to Rwanda -- central to his re-election pitch -- would not happen before polling day.

A bill compensating tens of thousands of victims of an infected blood scandal was set to pass, however, while legislation clearing the names of people wrongly convicted of fraud in a Post Office scandal was due to receive royal assent and become law.

The main opposition Labour party, led by Keir Starmer, are ahead of Sunak's ruling Conservatives by double digits in opinions polls but require a huge swing to win a majority and form the next government.