China has gone all out to ensure security for the games, deploying such hardware as surface-to-air missiles near sports venues and more than 100,000 security personnel for the games, which begin on Friday and end on August 24.
Neil Fergus, who was the director of security intelligence at the 2000 Olympics in Sydney, said China's security preparation for the games was "second to none".
"At this stage there's no reason to think that the Beijing Olympic games are any less secure than previous games and in fact they may be the most secure games we've ever seen," he said.
Chinese state media has said Monday's attack on a border police station in the city of Kashgarwas "likely" carried out by the East Turkestan Islamic Movement.
Two armed men drove a lorry into a group of police officers jogging outside the building and threw two grenades before attacking them with knives, local media reported.
"On the scene, police also found two knives used in the attack and some propaganda material advocating a 'holy war'," a public security ministry statement said.
Shi Dagang, the Communist Party secretary of Kashgar, said on Tuesday: "Xinjiang police have already 18 terrorists from abroad."
However, he gave no timeframe for the arrests and made the statement after detailing a list of security incidents this year.
The authorities announced sweeping security checks on all transportation in Xinjiang on Tuesday and tightened checks at the airport in the province's capital Urumqi, resulting in long passenger queues waiting to get through security checkpoints.
"The whole region's transport network must establish a dense atmosphere of secure transport and production," the region's state media reported, citing an "urgent directive" from the government.
The police presence at roads into the city jas been increased and extra security ordered in public places, including government office buildings, schools and hospitals, Xinhua said.
Meanwhile, an exiled leader of China's Uighur Muslims condemned the attack but urged the government not to punish the innocent.
"We condemn all acts of violence," Rebiya Kadeer said in Washington, where she has been living in exile since 2005 after spending six years in a Beijing prison.
|State media reported that two suspects were arrested after the attack [Reuters]
"The Uighur people do not support acts that engender bloodshed."
Urging the Chinese government "to refrain from using this incident to crack down further upon peaceful Uighurs", Kadeer said the incident "will only serve to increase suppression of the Uighur people and exacerbate tensions between Uighurs and Han Chinese".
Kadeer's Uighur American Association said it was seeking independent accounts of the incident and urged caution over unsubstantiated official Chinese accounts.
Xinjiang's largely Muslim Uighurs have been a focus of China's security crackdown in the run-up to the games, with officials saying separatists from the region are among the biggest threats.
Many Uighurs resent Chinese controls on religion and the expanding ethnic Han Chinese presence in Xinjiang, a region rich in energy and mineral resources.
"We are scared that after this things may be even harder for Uighurs," Ibrahim, a shopper in Kashgar's main market, said. "There's already a lot of tension here."