NEW YORK (CNN/Money) - British telecom Vodafone put in an official bid for AT&T Wireless of about $35 billion, the Wall Street Journal Online reported Sunday, citing people close to the situation.

Cingular Wireless Friday raised its offer to buy AT&T Wireless Services also to about $35 billion, sources familiar with the deal told Reuters, triggering a bidding war for No. 3 U.S. wireless company.

Because the bids submitted so far are roughly similar, the bidders were asked to hand in a second round of offers Sunday, the Journal said.

Citing people close to the situation, the paper said a decision between Vodafone and Cingular could come soon, though AT&T Wireless has given itself two weeks after the bids are filed.

But analysts and traders Friday said AT&T Wireless had no reason to rush and may wait until its self-imposed Feb. 29 deadline, especially since the two suitors may return with sweetened offers.

"Why rush to a decision? Make them sweat it out and worry whether or not they won and see if you can get them to come back with better offers," said one arbitrageur, who declined to be named.

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Hopes of a bidding war sent AT&T Wireless (AWE: Research, Estimates) shares to 12- month highs of $11.98, valuing the group at $32.56 billion Friday. The stock closed at $11.82, up 15 cents, or 1.29 percent, on the New York Stock Exchange, where it was the most actively traded stock.

The heated interest in AT&T Wireless comes even as the company recently suffered an unexpected fourth-quarter loss and warned that technical and customer-service problems would lead to drop in customers throughout the first half of 2004.

NTT DoCoMo Inc. (DCM: Research, Estimates), which owns 16 percent of AT&T Wireless, Friday decided against submitting a bid after determining it lacked the staff or bulk to realistically acquire and operate a company as large as AT&T Wireless, one source said.

In January, AT&T Wireless lost nearly 4 percent of its customers and saw its operating income fall more than 20 percent from a year ago, sources close to the situation have said.

While some Vodafone (VOD: Research, Estimates) investors remain unconvinced about the merits of a bold offer, a growing number believe Chief Executive Arun Sarin would fight for an asset that would give the group long sought-for control of a company in the world's most powerful economy and bring its brand across the Atlantic.

"We are supportive of Vodafone, but on the information currently available, we are skeptical as to whether the deal at the prices talked about will generate an acceptable financial return," said David Cumming, the head of UK equities at Standard Life Investments.

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Analysts were split on which company would be the victor.

"If Vodafone is in, they're in it to win. Vodafone doesn't bid to lose. They might force Cingular to look at T-Mobile" and give up on AT&T Wireless, Patrick Comack of Guzman &Co. said on CNBC.

Meanwhile, Cingular, the No. 2 U.S. wireless company, has the deep pockets of its parent companies, SBC Communications Inc. (SBC: Research, Estimates) and BellSouth Corp. (BLS: Research, Estimates), to make an aggressive bid.

"It is scale -- Cingular, versus scope -- Vodafone," said Raul Katz, head of the telecommunications practice at Booz Allen Hamilton.

"Cingular is betting on cost synergies, particularly the opportunity to work on redundant infrastructure overhead, while Vodafone is betting on economies of scope, trying to apply the same aggressive recipe they have used in Europe to the U.S.," Katz added.