Paratroopers hurtling head first out of planes, attack helicopters strafing a terror training centre and shacks blown to bits were this week's latest embodiment of China-Pakistan friendship.

The war games conducted by 540 Chinese and Pakistani soldiers running around scrubland -- the fourth joint exercises since 2006 -- were ostensibly a chance for China to benefit from Pakistan's counter-terrorism experience.

There was disappointment that fighter jets were unable to carry out a bombing raid, with visibility apparently poor, but the exercises were declared a success in terms of deepening friendship and improving military cooperation.

But behind the pomp rolled out for the Chinese, complete with slap-up marquee lunch and bags of presents, the relationship is as transactional as any other, as China competes with Pakistan's arch-rival India for Asian dominance.

And it is far from easy to decipher. "They operate silently so as not to make any statements in public apart from cliches. So one doesn't know what's happening," said retired Pakistani general Talat Masood.

China is Pakistan's main arms supplier, while Beijing has built two nuclear power plants in Pakistan and is contracted to construct two more reactors.

But the alliance has been knocked by Chinese accusations that the separatist East Turkestan Islamic Movement (ETIM), which wants an independent homeland for Xinjiang's Muslim Uighurs, is training "terrorists" in Pakistani camps.

Those accusations mirror long-standing concerns from the United States that Taliban and Al-Qaeda bases are funnelling recruits to fight in Afghanistan and hatch terror plots against the West.

During the exercises outside Jhelum, 85 kilometres (50 miles) southeast of Islamabad, generals watched troops attack, clear and destroy a mocked-up training camp, while smoking and sipping cups of tea under a giant tent to keep off winter rays.

Chinese deputy chief of staff Hou Shusen and Pakistan's army chief Ashfaq Kayani sat together in the front row, guests of honour incapable of talking to each other without the help of an interpreter.

"We have done our utmost to eliminate this threat of ETIM and other extremists for China because we consider honestly that China's security is very dear to Pakistan," Kayani told a news conference after the war games.

He said that Pakistan had provided intelligence during the 2008 Beijing Olympics and the 2010 Shanghai Expo, and reiterated demands for closer military cooperation and larger imports of military hardware from China.

Beijing was instrumental in getting the United Nations and United States to blacklist ETIM as a terrorist organisation in 2002, but experts have questioned how much of a threat such a small group of people really poses.

Pakistani analysts believe members number no more than hundreds and are fairly dispersed in the remote mountains on the Pakistan-China border.

Despite that issue, if the language used to describe Pakistan's febrile relationship with the United States is that of an unhappy couple wishing but unable to divorce, then the hyperbole used to describe China is that of an ecstatic lover.

"Higher than mountains" and "sweeter than honey" were phrases used by Prime Minister Yousuf Raza Gilani when Chinese Public Security Minister Meng Jianzhu came to town in September, at a time when relations with the US were at their most difficult in years.

The top US military officer, Admiral Mike Mullen, had just accused Pakistan of colluding with Afghan militants in besieging the US embassy in Kabul as ties plummeted further after the raid that killed Osama bin Laden.

But independent China analyst Michael Dillon says that without any real ideological links, China's relationship with Pakistan is primarily strategic, designed to offset its rivalry with India.

"There is a feeling that cooperation with Pakistan on counter-terrorism might be in China's interests," he told AFP.

"They've got economic domination over Southeast Asia. But South Asia is another matter. The big rival is India. If they can get close diplomatically to Pakistan then it can balance the power of India in the subcontinent," he said.

Neither can China present an alternative to the US alliance.

But Kayani described China as "very important" to regional stability, perhaps best seen against a backdrop of Pakistan's own rivalry with India.

"It's not a zero-sum game. You further strengthen your relations with China, then you increase your importance. You use this as a leverage to improve your relationship with the US," said Masood.