Reporters besieged the London studios of Evans' station, Virgin Radio, from before dawn on Thursday after the story was splashed across tabloid front pages.

It is reported they have been seeing each other for a number of weeks - with one newspaper claiming the two are about to announce their engagement.

But the former Ginger Spice refused to talk about it when she appeared on the breakfast show at London pop radio station Kiss 100.

Presenter Peter Poulton, who goes under the on-air name of Bam Bam, said: "She was due to be on air at 9am for an hour, but she came in at ten to nine and we were told no questions about Emma Bunton, no questions about Chris Evans, and I'm out of here at nine o'clock.

"When I handed over to the newsreader he asked her about it. She was going to walk out, but she stayed. She didn't answer though."

Geri Halliwell: Has an autobiography and single to promote

Instead, she gave listeners tips on stress relief, which included taking off her shoes and walking in the park.

She did refer to "a new friend" - but said no more.

Meanwhile at Virgin, 33-year-old Evans made an indirect reference to the story on his breakfast show - saying a report that Halliwell, 27, had no luck with men was "yesterday's news".

He avoided reporters earlier by entering the station by a back door, but later quipped: "What are all those photographers doing outside? Is there a new kind of crisp being launched?"

He signed off saying: "It's going to be a long day."

Evans' co-presenters also declined to comment on the story. Holly Samos said: "He hasn't told me anything I don't know."

Dan McGrath said, smiling: "I can't possibly talk about things like that."

The arrival of a chauffeur-driven car containing a shih-tzu dog caused a stir among reporters later in the morning - Halliwell has a shih-tzu, though it is not known whether it was her dog in the car or if it was a publicity stunt. The dog was later driven away again.

Mel C: Not talking about "the gingers"

In the afternoon, Halliwell's old group held a press conference in central London to promote their book, Forever Spice.

But reporters hoping for a comment from the Spice Girls were disappointed. Sporty Spice Mel C said: "We're here to talk about the book, not about the gingers.

"If it's true, congratulations and good luck."

When the Spice Girls' debut single, Wannabe, was released in 1996, Evans was critical of it, attacking the group on air.

But relations between Evans and the group warmed over time, and he was reported to have had a role in Halliwell's decision to leave the group in May 1998.

The two not only share the same hair colour, they also share the same publicists, Freud Communications, and teamed up earlier this year to promote the Comic Relief charity appeal.

Halliwell is currently engaged in a publicity battle with former colleague Emma Bunton after they both simultaneously released singles on the same day.

Midweek chart figures show Halliwell's single, Lift Me Up, is 5,000 copies ahead of Bunton's single, What I Am, a collaboration with dance act Tin Tin Out.