Tonga's opposition Democratic Party says the government planned the development of the Vuna Wharf in Nukualofa poorly.
It says unfinished parts of the wharf are an eye-sore and a potential threat to the environment.
Funded with a 17 million US dollar loan from China, the wharf is open for cruise ships while a section earmarked for a marina is incomplete as more funds are being sought to complete it.
The oppostion leader, Akilisi Pohiva, says the project has been flawed.
"My view is that the other part that is yet to be finished spoils the whole scene. I think the government is now looking for funds. There is no way that our current budget or the next budget, there is no way the government can allocate part of the next budget for this particular project. It is a waste of our limited resources."
At least three cruise ships have used the wharf since it was officially opened last year.