DEFENCE Minister Joel Fitzgibbon said last night he had failed to declare two trips to China paid for by Helen Liu, the Chinese-Australian businesswoman at the centre of a national security row. He apologised and said the trips were paid for by Ms Liu or her companies in 2002 and 2005. "This was a mistake and for that I apologise," he said in a statement.He also received a suit from her last year but said he returned the gift within weeks. The Defence Department said yesterday it would investigate claims that officials had conducted a covert probe into Mr Fitzgibbon's links to Ms Liu, who has been mentioned in Australian intelligence reporting regarding her ties to Beijing. Ms Liu is well-connected in China, having rubbed shoulders with a range of senior leaders including the former premier Li Peng. A website for expatriate Chinese reported Ms Liu kept good relations with Australian politicians and "accurately passed new Australian policies and moves towards China to relevant domestic parties". Intelligence officials in Canberra have noted Ms Liu's business activities and contact with Chinese Government officials in the context of Chinese Government activity in Australia. Speaking at the RAAF base at Richmond yesterday, Mr Fitzgibbon said no concerns over his relationship with Ms Liu had ever been raised with him. "I've said on a number of occasions I've had a close personal relationship with the Lius for some 16 years now, and over that period of time there's been an exchange of a number of small gifts." Mr Fitzgibbon said his plans to reform the Defence Department might have prompted elements within his department to pry into his personal affairs. Defence officials who conducted a covert investigation into Mr Fitzgibbon's relationship with Ms Liu were also said to be concerned about her relationship with high-ranking Chinese officials and agencies. Defence Department secretary Nick Warner said the Defence Security Authority would investigate whether officials had conducted a covert investigation into Mr Fitzgibbon's personal affairs. The Fitzgibbon family relationship with the Lius went back more than 20 years, Joel Fitzgibbon's father Eric said yesterday. He recalled that in 1986 he took Joel on a visit to China, where they met Ms Liu, her brother Xue Dong and her sister, known as Queena, in Quingdao. A wine grower from the Hunter introduced him, "probably [at] some sort of dinner", Mr Eric Fitzgibbon said yesterday from Cessnock. Two of Ms Liu's former Sydney property development companies have contributed about $90,000 to the NSW ALP. He said his son did not have an affair with Ms Liu and she was no threat to national security. "What people may think is that there is an illicit affair between Joel and Helen Liu or that she is a spy and is trying to get official information," he said. "It is crazy." Joel Fitzgibbon's brother Mark said Ms Liu had been a longstanding family friend. SMH