"We can't confirm that a visit will happen," a Foreign Office spokesman told AFP, saying Britain needed to discuss the issue with "our French and German partners."
Britain would "make clear to Iran the urgent need to act on the international concerns over its nuclear programme," and to cooperate with the International Atomic Energy Agency (IAEA), he added.
Iranian Foreign ministry spokesman Hamid Reza Asefi said Sunday that Iran had been negotiating with three countries after they sent a letter offering technical assistance in return for Tehran assisting the IAEA.
"Since the foreign ministers of Germany, Britain and France have sent us a letter showing their inclination to cooperate with us, we have decided on a constructive dialogue," Asefi said, adding that talks have been going on "for several days".
"It is possible in the coming days that this will reach a higher level -- so we have invited to Iran the three foreign ministers to give their points of view," the spokesman said.