Although Tsang said he paid for the helicopter flight during a holiday on Phuket earlier this month, he did not reveal the cost.
The chief executive of Hong Kong, an international city that remains an important gateway to China, admitted taking a luxury yacht trip offered by a tycoon during a private visit to the gambling hub of Macau.
But he insists he has not breached bribery laws in the city that was once famous for its high level of corruption.
Under Hong Kong's tough anti-bribery laws, the chief executive is barred from any acts of "solicitation and acceptance of advantage and possession of unexplained property".
He must declare all gifts valued over HK$400 (US$52).
''I am saddened by the reports which questioned my integrity and suggested there is a collusion between the government and businessmen,'' Tsang told public broadcaster RTHK, which said he called the station to offer an explanation.
The Oriental Daily newspaper reported that Tsang and his wife flew to Phuket on February 9 on a private jet, together with around a dozen tycoons, for a four day holiday, reported rthk.com.
It said he'd been invited by property tycoon Zhang Songqiao - who's sometimes referred to as ''the Li Ka-shing of Chongqing.'' [Li Ka-shing is Hong Kong's richest billionaire]
The newspaper report quoted the chief executive's office as saying that Tsang had reimbursed the owner of the plane for the trip, an amount that's around the same as the cost of a commercial flight.
Tsang visited Phuket just a week before taking another holiday in Macau - during which he stayed on a tycoon's luxury yacht.
Pressure has mounted this week on Tsang after Hong Kong media published pictures of him and his wife spending a weekend on the triple-deck luxury boat off Macau, a casino island near Hong Kong, with a few tycoons last week.
His wife is from Macau.
Tsang's term is due to expire in June. The Phuket helicopter holiday trip is a new element among rising criticism. Details of the Phuket flight have yet to emerge.
Skydance by Advance Aviation, which operates helicopters on Phuket that are mostly used for adventure flights over the beaches and Phang Nga Bay, could not confirm today whether Tsang had been on one of their flights.
Hong Kong, a city of seven million, has one of the world's highest income gaps between rich and poor. A consistent criticism is that the government colludes with big business.