Lazaro had been due to appear for a bail hearing on Thursday, but a judge delayed his hearing - along with those of four other suspects - until Friday.

The judge ruled that Pelaez, who has US citizenship, can be released under house arrest with $250,000 bond. The remaining suspects were denied bail and will remain behind bars.

Michael Farbiarz, the prosecutor, told the New York federal magistrate judge that he considered all of the suspects to be flight risks.

'Sophisticated network'

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The group, who were arrested on Sunday in Boston, New York and the Washington area, have been accused of trying to infiltrate US policymaking circles, but have not been officially charged. 

Donald Howard Heathfield and Tracey Lee Ann Foley, arrested by the FBI at their home after years of surveillance operations, were two of the suspects denied bail. They will remain in custody in Boston pending another hearing on July 16. 

Al Jazeera's Nick Spicer, reporting from Washington DC, said that Foley asked to be referred to as "person number five" during court proceedings.

"This suggests a legal strategy whereby the accused will say it is up to the US government to prove who they say they are," he said.

"The other thing that the accused asked for was to meet in prison so they could discuss what to do about their children ... there are a number of children involved in this so-called spy ring and some of those are in US federal custody at this point."

A court filing said both Heathfield and Foley had claimed to be Canadians, but the former was using the birth certificate of a dead Canadian boy, while a search of a safety deposit box belonging to the latter found photographs of her developed by a Soviet film company.

'Extremely thin' evidence

Speaking after the hearing, Peter Krupp, Heathfield's lawyer, described the evidence against his client as "extremely thin".

Metsos disappeared after being granted
bail in Cyprus [AFP]

"It essentially suggests that they successfully infiltrated neighbourhoods, cocktail parties and the PTA [Parent Teacher Association]," he said.

A hearing in Virginia was postponed after attorneys for two other suspects Michael Zottoli and Patricia Mills said they had just received new information from prosecutors. Mikhail Semenko, another suspect, had not yet got a lawyer.

Anna Chapman, 28, a tenth suspect, had an earlier bail request denied on Monday.

The chances of any of the suspects being granted bail had seemed slim after an 11th suspected disappeared after being released on bail in Cyprus.

Cypriot police are now hunting for Christopher Robert Metsos, who purports to be a Canadian citizen.

He is accused of being the paymaster for a "deep cover" cell of spies in the US, furnishing them with money and swapping bags covertly with other Russian operatives.

Cypriot police 'hopeful'

Metsos was arrested early on Tuesday at Cyprus's Larnaca airport as he tried to board a flight to Budapest but was not deemed enough of a flight risk to be kept behind bars until he could be extradited to the US.

There was no sign of him when Cypriot police rushed to his hotel room on Wednesday after he failed to sign in at a Larnaca police station in terms of his bail.

"We are disappointed that Christopher Metsos was released on bail following his arrest in Cyprus," Philip Crowley, the US state department spokesman, said.

"As we had feared, having been given, unnecessarily, the chance to flee, he did so."

Loucas Louca, the Cypriot justice minsiter, said he was hopeful that Mestos would be rearrested on the island.

"We know his whereabouts roughly from the information we have collected," he said. "We have some information, and I hope that we will arrest him soon."

Police said all exit points from the Mediterranean island were being monitored as was the border with the north of the divided island.