LONDON (Reuters) - Britain said on Wednesday two birds held in quarantine, not just the one parrot identified, may have had H5N1 bird flu virus and that 32 others that died in captivity were now being tested. 

Authorities said on Sunday avian influenza was found in a parrot that died in quarantine east of London. 

They said its tissue sample had been pooled with that from another bird in the testing process, making it possible, but not certain, that a second bird had also been infected. "We now consider the virus was found in samples taken from two birds ... which had died       on       October    16,"

Environment, Food and Rural Affairs Secretary Margaret Beckett told parliament.  An official at her department said Beckett's statement had not meant to indicate it was certain

the second bird had been infected but that it remained possible and tests were ongoing. 

"As yet, we can't tell," she said. The birds were among two batches from Surinam in south America and Taiwan that were kept together. Experts are working on the hypothesis that the virus came from Taiwan and was transferred during quarantine. 

Beckett said other birds had died in quarantine before October 16 and that 32 of those were kept for analysis in a freezer. She said they may also have been infected with an H5 flu virus but not necessarily the deadly H5N1 strain. 

"Initial tests, which have not yet been validated, identified that H5 is present in some of these birds," she said. "We have not yet established the full circumstances of these deaths." 

Beckett insisted that as all birds had died in quarantine, the system had worked effectively: "It ... means that our disease-free status on avian flu remains unaffected." The European Union on Tuesday banned imports of captive live birds from other countries to strengthen its fight against bird flu after the British parrot case came to light.