BEIJING: Pakistani Prime Minister Yusuf Raza Gilani will visit China from Tuesday, after last week opening his country's second Chinese-made nuclear power reactor at the Chashma complex.

Here are some questions and answers about the Chashma, China's role in Pakistan's nuclear sector, and the concerns those issues have raised.

WHAT IS THE CHASHMA COMPLEX?

Chashma is the site of a Pakistani nuclear power complex built using Chinese expertise and designs. One 300 megawatt pressurized water reactor began commercial operation in 2000, and Chinese companies recently completed another unit of similar size that was opened on May 12.

Chinese nuclear companies plan to build two more reactors at Chashma. They have not issued detailed information about when they will start, but contracts have been signed and financing is being secured.

WHY IS CHINA HELPING BUILD MORE REACTORS THERE?

Converging foreign policy and commercial motives appear to be driving China's decision. Pakistan is a long-standing partner of China, and Beijing believes it important to back Pakistan to counter Indian regional dominance.

It is also wary of the US sway across south Asia, and Washington signed a nuclear energy deal with India in 2008 that China and other countries found questionable.

Pakistan faces acute power shortages, and demand is likely to keep growing as its population expands, although nuclear reactors will take many years to go on line and ease shortages.

There's also a commercial pull. Chinese nuclear companies want to win foreign markets, and for now Pakistan is the only springboard they have to hone their skills abroad in the hope that they will later attract foreign customers elsewhere.

ARE THERE NUCLEAR PROLIFERATION RISKS?

In theory, Pakistan could at some later date take spent fuel from Chashma to reprocess it for plutonium that could be used for nuclear weapons.

In practice, however, the International Atomic Energy Agency keeps safeguards at Chashma to stop that happening, said Mark Hibbs, an expert on atomic policy at the Carnegie Endowment for International Peace. The IAEA agreed in March to Pakistan's request that it safeguard the two new reactors planned for Chashma.

SO WHAT ARE OTHER GOVERNMENTS WORRIED ABOUT?

Some of the worry is about Pakistan and some is about the integrity of nuclear non-proliferation rules.

There are those, including many commentators in India, who say Pakistan is so dogged by instability and militant pressures that it should not receive nuclear technology, which could be the target of attacks.

Pakistani nuclear scientist A.Q. Khan was a key broker of illicit nuclear technology to Iran, Libya and North Korea, and critics say that precedent is a powerful reason to worry.

The more broadly shared concern is that, however secure Chashma may be, expanding the nuclear complex there could be a fresh blow to the integrity of nuclear non-proliferation rules.

Pakistan tested nuclear devices in 1998, soon after India held similar tests, and both nations refuse to join the Nuclear Non-Proliferation Treaty, which would oblige them to scrap nuclear weapons.

Both India and Pakistan have been expanding their nuclear arsenals, and within a decade Pakistan may become the fourth largest atomic weapons power, behind the United States, Russia and China, some Western experts have estimated.

The NPT rules say if countries not authorised to possess nuclear weapons want to receive nuclear materials from countries adhering to the treaty, they should accept comprehensive safeguard agreements for nuclear activities.

WHAT CAN THEY DO?

For now, the main arena for addressing this issue is the Nuclear Suppliers Group, a 46-member body that seeks to ensure nuclear exports are not diverted to non-peaceful purposes.

To receive nuclear exports, nations that are not one of the five officially recognised atomic weapons states must usually place all their nuclear activities under the safeguards of the International Atomic Energy Agency, say NSG rules.

When the United States sealed its nuclear agreement with India in 2008, it won a waiver from that rule from the NSG after contentious negotiations. Washington and other governments have said China should at least seek a similar exemption for the planned reactors in Pakistan.

There is also little likelihood of all 46 member governments of the NSG voting in favour of a waiver, and this is a group that operates by consensus.

Beijing is likely to shun calls to seek a waiver, and argue that the two units planned for Chashma come under a bilateral agreement sealed before it joined the NSG in 2004.

At least some NSG members, including the United States, may ultimately accept a compromise whereby China agrees the two reactors planned for Chashma will be the last it claims do not need approval from the group, said Hibbs, the nuclear expert.