Illegal networks selling nuclear technology to the highest bidder on the black market are posing a greater threat than ever, an expert has warned.
Mr Hibbs obtained centrifuge blueprints on the black market
A speaker at non-proliferation talks in Washington said technology essential for enriching uranium was now freely available on the black market.
Others said that efforts to tackle the problem were tepid and in disarray.
The conference also raised concerns that the issue has receded from the non-proliferation agenda.
Mark Hibbs, an editor with the journal Nucleonics Week and one of the world's most prominent experts in the field, told the Carnegie Endowment for International Peace conference that barriers to nuclear technology had broken down significantly.
He said he had been able to obtain blueprints for a type of centrifuge dating from the 1960s that had taken European scientists decades to develop.
The design had been stolen by Pakistan in 1974 and was subsequently marketed by AQ Khan, the disgraced nuclear scientist who supplied his expertise to Libya, North Korea and Iran.
Our correspondent says that despite the unmasking of the AQ Khan network, the whole issue has faded from the non-proliferation agenda.
Mr Hibbs said the information was now out there and could be bought by anyone with sufficient funds.
He added that the black market was constantly shifting to keep ahead of international investigators.
He also warned that the problem of nuclear smuggling might become worse as the demand around the world for civil nuclear power outstrips the ability of legitimate suppliers to meet the demand.