Foreign office minister Alistair Burt has warned that "miscalculations" about the extent of Iran's nuclear programme are possible, if the country doesn't reveal its exact intentions to the international community.
Burt said that the UK government - clearly mindful of the mistakes made about Saddam Hussein's WMD programme - was "aware that there are problems with miscalculation based on a lack of information," and urged Tehran to disclose the nature of its nuclear capabilities, "rather than leave it to the rest of us to make a guess about what its intentions are."
"We know that mistakes are made when information is uncertain and miscalculations are made because of a lack of information. What we do know with absolute certainty that the Iranians are on track to a situation of great danger. If they want to de-escalate this, they know exactly what they have to do."
Speaking to the Lords EU Scrutiny Committee on Thursday morning, Burt warned that Iran didn't have long to come clean about its nuclear programme, before "a situation of no return has been passed. That is the danger inherent in all this.
"There are various calculations being made. President Obama said that the timescale for the Iranians to deal with this concern is shortening. That is the impression and the advice that I am getting."
"In order to prevent miscalculations being made the time is right now for the Iranians to be thoroughly open about its programme. If it does not, it is taking a grave risk."
Burt also told the Lords that there was evidence that Iran was seeking to further its ballistic missile range, with new delivery systems with which it could launch attacks on "a number of European countries," adding that UK troops in Afghanistan fell well within Iran's current maximum missile range of about 2,000 kilometers.
One peer suggested that presumably Iran wouldn't be developing new delivery systems unless it was planning a delivery system for a nuclear bomb?
"You may say that, my Lord," said Burt, before admitting "there is a linkage."
Burt admitted that sanctions had so far failed to curb the Iranian nuclear programme, but insisted they had been "effective to some degree," because they had at least brought the Tehran government to the table at the beginning of 2011 for the Istanbul talks.
That those talks failed to achieve anything didn't dissuade him from the merits of possible fresh sanctions, considered likely to be introduced by the US and EU later this year.