The Papua New Guinea finance minister, Bart Philemon, has told the Post Courier newspaper that it will be difficult to meet the budget targets because of the closure of the Porgera mine.
A supplementary budget presented after the new government took office last month was approved by parliament without dissent.
The budget was drawn up to avoid a massive deficit by the end of the year and was described as the only responsible option available to the government.
Mr Philemon says the closure of Porgera because of the destruction of power lines will reduce tax revenue by about 15 million US dollars which means that financing the deficit will be a struggle.
Meanwhile, the opposition leader, Sir Mekere Morauta, has rejected criticism of the former government's handling of the finances.
Sir Mekere says claims that his then administration's budget was headed for a blow-out was misleading.