BRUSSELS, March 3: The head of the United Nations nuclear watchdog on Tuesday lauded Pakistan's cooperative stance in combating nuclear proliferation and said the International Atomic Energy Agency (IAEA) was making "very good progress" in tracking down a long list of European middle men and companies involved in illicit sales of nuclear technology and equipment.

"Pakistan is cooperating. The authorities have given us assurances that they are putting in place measures to have full control" over any future nuclear leaks, IAEA chief Mohamed ElBaradei told reporters in Brussels.

The IAEA was making "very good progress in identifying all people involved" in the extensive international proliferation network which had Pakistani scientist Abdul Qadeer Khan at its centre and spanned several continents, ElBaradei said.

"We have a good picture of who is involved and where in Asia, Europe and the Middle East," he insisted, adding that authorities in several countries were tracking down their nationals involved in the blackmarket.

It was crucial that the international community learned from experience and such leaks of nuclear technology were not replicated, ElBaradei insisted. Diplomats in Vienna say the network being investigated stretches wide, including Japan, Malaysia, Pakistan, South Africa, Spain, Germany, the Netherlands and Switzerland.

The IAEA inquiry is being undertaken with the help of national authorities in the countries concerned and any action taken against those charged will be under national criminal jurisdiction. But the investigation is still believed to be in its early stages.