Beijing, Feb 13 : Beijing has denied any knowledge of the three "airborne objects" that the US military shot down in North American airspace over the weekend as China prepares to take down an unidentified flying object near one of its main naval bases, media reports said. Chinese Foreign Ministry's spokesperson Wang Wenbin told reporters in Beijing on Monday that any suggestion that they came from China is just a "smear", RFA reported. The US North American Aerospace Defense Command (NORAD) announced that "an F-16 fired an AIM9x to successfully shoot down an airborne object flying at approximately 20,000 feet altitude in the US airspace over Lake Huron in the state of Michigan" at 2:42 p.m. on Sunday. This object was first spotted on Saturday over Montana, when it flew near sensitive military sites, U.S. officials told the media, RFA reported. However, NORAD said it was not assessed "to be a kinetic military threat to anything on the ground," but a safety flight hazard and "a threat due to its potential surveillance capabilities." Before this, a "high-altitude object" was shot down on Saturday over the Yukon territory in Canada and another "flying object" on Friday off the Northern coast of Alaska, both by US F-22 fighters. Authorities have yet to determine whether the flying objects are linked to China as recovery efforts continue, RFA reported Meanwhiloe, China's Foreign Ministry said the US has flown balloons into its airspace more than 10 times in the past year, BBC reported. Questioned on Monday, Beijing said the US had made many airspace breaches. "It's not uncommon as well for the US to illegally enter the airspace of other countries," said Foreign Ministry spokesman Wang Wenbin at a regular press briefing. "Since last year alone, US balloons have illegally flown above China more than 10 times without any approval from Chinese authorities. "The first thing the US side should do is start with a clean slate, undergo some self-reflection, instead of smearing and accusing China," he added. He said Beijing had responded to the incursions in a "responsible and professional" manner. "If you want to know more about US high-altitude balloons illegally entering China's airspace, I suggest you refer to the US side," he said, BBC reported. /IANS