Tasmania's Environmental Protection Agency (EPA) has come under criticism for its handling of a drilling platform moored in the River Derwent, with the seafood industry calling for reform of Tasmania's biosecurity laws.

Key points: The presence of the Ocean Monarch drilling platform in Hobart has raised biosecurity concerns

The presence of the Ocean Monarch drilling platform in Hobart has raised biosecurity concerns The rig's owners Diamond Offshore refused to let the EPA conduct an inspection

The rig's owners Diamond Offshore refused to let the EPA conduct an inspection Instead, it will conduct its own and provide the EPA with the report

The Ocean Monarch, which has been drilling for gas in the Bass Strait off the east Gippsland coast, was towed to Hobart in early November for maintenance and minor repairs.

In mid-December, salmon company Tassal raised concerns with the EPA about potential biosecurity risks posed by the rig.

The EPA confirmed it was worried the marine pest Didemnum perlucidum, also known as the white colonial sea squirt, could be on the platform's submerged sections.

The rig's owner Diamond Offshore refused to allow the EPA to inspect for the marine pests, but agreed to have an inspection and provide the EPA with the report.

Environment Tasmania's Philip Cocker questioned the decision to allow the company to self assess.

"It seems very strange to us that the company that would be liable if a pest is found … is going to be the [one] responsible for reporting the outcomes of the check," he said.

He said the EPA should have inspected the rig before it came into the river.

"It's a little late after it's been sitting there for a month to start talking about assessing the risk and putting pressure on the company to do the right thing," he said.

Mr Cocker said the "lack of transparency around the EPA and the biosecurity rules needs to be addressed".

Different standards are being applied: Oysters Tasmania

Oysters Tasmania chairman Ben Cameron said his concern was less about a specific company or vessel but rather overarching biosecurity laws.

"If I want to move oysters, I have to do all the biosecurity before that happens," he said.

"I have to prove we're not moving pests or diseases before that goes even inside our state, let alone interstate."

Mr Cameron questioned why different industries were held to different standards, and said it should be uniform across all users of the waterways.

"We need to have a harmonised system across sectors because at the moment oysters is different to salmon," he said.

"We just had a row over Norfolk Bay [with the salmon industry because there are] two different sets of standards."

He said everything from oil rigs to cruise ships should be held to account.

The Tasmanian Seafood Industry Council also raised concerns about the state's biosecurity laws at both state and federal level.

No legal requirement to inspect Ocean Monarch: EPA

EPA director Wes Ford said there was no legal requirement for something like a drilling rig to be inspected.

"My decision to undertake an inspection in late November was based on advice I received from the Commonwealth around the risk assessment work that had been undertaken," he said.

"There are no environmental requirements by the EPA for vessels entering Tasmanian waters."

He also said any company regulated by the EPA could undertake its own data collection and provide the information to the EPA for audit and review.

In a statement, a Tasmanian Government spokesperson said the EPA was "regulating" the potential environmental impacts of the Ocean Monarch.

"In regards to the Ocean Monarch, the independent EPA is regulating potential environmental impacts, including noise, waste and marine biofouling via Environment Protection Notice," it said.

"This is a visiting vessel and little different to the cruise ships and tankers that come into the river every day."

Diamond Offshore is due to conduct its inspection this weekend pending weather conditions.

The rig is scheduled leave Hobart in late January.