A mother has been jailed for seven years for attempting to sell her baby for £35,000.

The 29-year-old woman believed she was selling her 11-month-old baby girl to a childless couple at a meeting in a hotel in east London last September. But the couple turned out to be undercover reporters from the News of the World who alerted police.

After the exchange, the police, who were listening in an adjoining room, swooped in to arrest the woman, who cannot be named for legal reasons.

In April, she was found guilty at Inner London crown court of conspiracy to commit child cruelty and holding another person in slavery.

A 48-year-old estate agent who acted as a broker, and who also cannot be named, was sentenced to nine years in prison for the same offences. He had promised to provide forged birth certificates.

During the trial Christopher Foulkes, prosecuting, told the jury: "Slavery involves exercising over a person any or all of the rights of ownership.

"No one, not even a parent, is allowed to own another person. You may think that there is no better example of treating someone as if you own them than by deciding, or seeking or agreeing to sell them.

"And by doing this in relation to this child, these defendants held her in slavery."

The conspiracy surfaced when the estate agent told an associate, Asad Ali, that there was a "baby for sale".

Ali then informed reporters at the Sunday paper, who set up the sting at the Viking hotel, in Stratford, east London, on 22 September.

The woman's husband, who is not the child's father, was found innocent of all charges.

The manager of the three-star Viking hotel, Hygine Paveer Anthony, said he was totally unaware of the operation. "We didn't know that the police were here. It was all undercover. We just gave the rooms out as if we were selling them to anybody else. And we didn't know about it until we saw the news the next day," he said.

"[The case] is really shocking especially since it was all happening in the middle of the day," he added.

In 2008 Canadian authorities arrested a couple who placed an ad on Craigslist, offering their seven-day old baby for $10,000 (£8,600). The advert read: "A new baby girl, seven days old, healthy and very cute … Can't afford and unexpected. Looking for a good home. Please call asap."

The parents, from Vancouver, were released after they claimed it was a hoax.

After the Stratford operation, Detective Chief Superintendent Gordon Briggs, head of the child abuse investigation command at Scotland Yard, said: "This was an appalling case where individuals have attempted to sell a vulnerable child for their own personal gain and with no consideration whatsoever for her safety and future."

The child is being cared for by Newham social services.