* News of the World closed in phone-hacking scandal

* Sun promises its journalists will abide by ethics code

By Tim Castle

LONDON, Feb 26 (Reuters) - Rupert Murdoch bid to grab back the huge audience his News Corp lost when it closed Britain's best-selling News of the World over a phone-hacking scandal with a new Sunday edition of his Sun tabloid filled with gossip, girls and celebrities.

With a front page splashing on a female TV presenter's birthing difficulties - "My heart stopped for 40 seconds" - the top-selling daily Sun made its Sunday debut, aiming to win back the 2.7 million people who had read News of the World until its closure in July in Britain's biggest recent press scandal.

News Corp's British newspaper arm News International closed the Sunday-only tabloid after disclosures it intercepted the voicemails of a murdered schoolgirl in a phone-hacking scandal that turned a spotlight on British newsgathering practices and reached to the highest levels of the government.

The ensuing furore shattered Murdoch's once close links to Britain's political elite as they distanced themselves from the magnate's tabloid titles and launched a far-reaching inquiry that could impose tough regulations on British newspapers.

News International has settled a string of legal claims in recent months over News of the World's phone hacking of celebrities and politicians, with Welsh singer Charlotte Church the latest to agree damages.

London police have arrested more than 30 people in three separate investigations linked to the scandal, including 10 current and former Sun journalists on suspicion of bribing public officials to get stories.

Sunday's Sun, launched at barely a week's notice and under the supervision of the 80-year-old media tycoon, stuck to its popular formula of quirky stories and reams of sports reporting.

TONED DOWN -- OR TAME?

In keeping with the family-friendly approach the paper takes on Saturdays, the daily's bare-breasted "Page 3 girl" was replaced by a singer in a slightly more modest pose, and sexual content was toned down in the agony advice column.

The tabloid also lacked any of the "kiss'n'tell" tales of bedroom encounters with soccer players and entertainers - and other exposes of the sexual infidelities of married celebrities - that were a staple of the scandal-loving News of the World.

But also missing was the kind of spectacular - and expensive - journalistic "sting" that defined the defunct Sunday paper, which over the years exposed lying politicians, loose-tongued royals and, most recently, match-fixing in international cricket.

"It feels very tame," Daily Telegraph media writer Neil Midgley told BBC television. But David Wooding, a senior reporter on the paper, said the aim was not to replicate the salacious former Sunday tabloid.

"If people are buying this who miss the News of the World, they are going to be disappointed, it is not the News of the World. It is The Sun," he told Sky News.

"VALUES OF DECENCY"

An editorial in the 120-page debut edition said the paper's reporters would abide by ethical conduct codes, seeking to distance itself from the methods that led to its predecessor's closure.

"We will hold our journalists to the standards we expect of them. After all, a newspaper which holds the powerful to account must do the same with itself. You will be able to trust our journalists to abide by the values of decency as they gather news," the paper said.

But it also acknowledged the arrests of its own journalists on suspicion of bribing public officials, noting that none of them had been charged.

"We believe those individuals are innocent until proven guilty. It has been a sobering experience for our entire industry," the paper said.

The launch of the Sunday Sun was widely expected and was a "no brainer" commercial decision for Murdoch's News International, according to researchers Enders Analysis.

Stretching the six-day Sun over a full week provides Murdoch a low-cost replacement for the News of the World, as well as utilising printing capacity left idle after the paper shut.

The launch gives News International a chance to regain part of 150 million pounds ($240 million) of annual revenue Enders estimates the News of the World generated from sales and advertising.

The Sun's Sunday success will be judged on how much it can claw back of the News of the World's former circulation.

"I will be very happy at anything substantially over two million," Murdoch said in a Twitter message.

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