Saudi Arabia has invested heavily in Pakistani nuclear weapons projects, and the cash-for-arms arrangement would help the Middle East country obtain atomic bombs at will, BBC quoted several sources as saying in its `Newsnight' programme.
Saudi Arabia, which is a signatory to the Nuclear Non-proliferation Treaty, started looking to Pakistan for N-arms support in the context of the nuclear threat from Iran, but the kingdom is in a position to deploy atomic weapons faster than the Islamic Republic, the report quoted military and diplomatic sources as saying.
Citing intelligence inputs from NATO and Israeli sources BBC said nuclear weapons made in Pakistan on behalf of Saudi Arabia are now ready for delivery.
"The Saudis will not wait one month. They already paid for the bomb, they will go to Pakistan and bring what they need to bring," BBC quoted Amos Yadlin, a former head of Israeli military intelligence, as telling a conference in Sweden on an Iranian N-bomb.
In fact, King Abdullah of Saudi Arabia had, in 2009, warned visiting US special envoy to the Middle East Dennis Ross that if Iran crossed the threshold, "we will get nuclear weapons," according to BBC.
"I do think that the Saudis believe that they have some understanding with Pakistan that, in extremis, they would have claim to acquire nuclear weapons from Pakistan," Gary Samore, former counter-proliferation adviser to President Barack Obama, told BBC Newsnight.
Saudis have been giving billions of dollars in development assistance to fellow Islamic country Pakistan. But, this has now turned out to be investments in future nuclear weapons.
''What did we think the Saudis were giving us all that money for? It wasn't charity,'' a senior Pakistani official told Newsnight.
According to BBC, Saudi Arabia's quest for acquisition of missiles capable of delivering nuclear warheads over long ranges goes back to the late 1980s, when it secretly bought dozens of CSS-2 ballistic missiles from China.
And 20 years after, defence magazine Jane's reported the completion of a new Saudi CSS-2 base with missile launch rails aligned with Israel and Iran.
Saudi Arabia has been giving generous financial assistance to Pakistan's defence sector, including for its missile and nuclear labs.
Saudi defence minister Prince Sultan bin Abdulaziz al Saud had also visited Pakistani nuclear research centre in 1999 and 2002, BBC quoted the report as saying.
Pakistan has been co-operating closely with China to acquire missile technology, including the design for a nuclear warhead as a strategic deterrent against India and passing it on to countries like Iran, Libya and North Korea, according to reports.
Western intelligence agencies had accused Pakistani scientist Abdul Qadeer Khan of selling atomic know-how and uranium enrichment centrifuges to Libya and North Korea.
Saudis, however, point out that their country had signed the Non-Proliferation Treaty, and call for a nuclear-free Middle East, pointing to Israel's possession of such weapons.
Pakistan also denies any such deal as the handing over atom bombs to a foreign government could create huge political difficulties for Pakistan.
Meanwhile, a paper leaked by senior Saudi officials during the US invasion of Iraq had mapped out three possible responses - to acquire their own nuclear weapons, to enter into an arrangement with another nuclear power to protect the kingdom, or to rely on the establishment of a nuclear-free zone in the Middle East.
The Saudis were not happy with the US execution of Saddam Hussein and its policy on Israel, while at the same time becoming increasingly concerned about the Iranian nuclear programme.
And, in 2007, the US mission in Riyadh had gathered information from Pakistani diplomats themselves about "Saudi-Pakistani nuclear cooperation".
This has also been substantiated by State Department cables posted by Wikileaks of a Pakistani comment, "it is logical for the Saudis to step in as the physical 'protector' of the Arab world by seeking nuclear weapons.
The Saudi thinking became louder in later years with the ruling princes and officials giving explicit warnings of their intention to acquire nuclear weapons if Iran did.