BEIJING (AFP) - China's defence ministry on Friday hit back at a US report which claimed Beijing underestimated its growing defence budget by nearly 20 per cent, state-media said.

In an annual report required by Congress, the Pentagon said that China's defence budget for 2013 was likely nearing US$145 billion (S$180 billion) last year, higher than the officially announced US$119.5 billion.

But China's defence ministry said in a statement that it "resolutely opposes" the report, state-run Xinhua news agency said.

The report "makes pointless accusations, exaggerates the 'Chinese military threat' and is a completely wrong course of action," Xinhua cited the ministry's information office as saying.

The news agency's dispatch did not directly address the claims that Beijing underestimated its defence budget.

The United States and its allies, especially Japan, have repeatedly voiced concern about the Chinese military's lack of transparency amid growing tensions between Beijing and neighbouring countries over maritime disputes.

Leaders of the Group of Seven industrialised nations said Thursday that they were deeply concerned by tensions in the East and South China Sea, in comments which did not mention China by name but were widely thought to be aimed at the country.

In its previous annual report on China, the Pentagon said that Beijing's military spending was anywhere between US$135 and US$215 billion.

China's military budget - either the official figure or Pentagon estimate - is significantly higher than the amount spent by its neighbours.

In 2013, Russia's defence budget was US$69.5 billion, Japan's was US$56.9 billion, with India at US$39.2 billion and South Korea at US$31 billion.

But China's budget is much lower than that of the United States, by far the world's largest military power, which has a US$495.5 billion defence budget in 2013 along with another US$82 billion allocated for the Afghanistan war.