Highland MP Drew Hendry has written to Transport Minister Robert Goodwill after maritime union Nautilus UK called for a rethink on emergency tug cut-backs.
The contract for the Orkney-based boat was recently renewed for six months, but will expire at the end of September.
Campaigners want to secure its future and there have also been calls for the reinstatement of a second emergency towing vessel (ETV).
Mr Hendry, the SNP’s transport spokesman at Westminster, said a union representative had described the current approach as “penny-pinching” and highlighted the contrast between UK Government policy on maritime safety and that of its European counterparts.
The former Highland Council leader added: “While the temporary U-turn was welcome, the fact remains that there is still a deficit of ETV coverage in the North Sea.
“As a result the UK Government has created unacceptable increased risk to seafarers and coastal communities alike.
“This call for a rethink from Nautilus is yet another clear message from those involved in the industry that current policy on maritime safety is not working.
“I have, therefore, once again written to the minister to ask that he listen and not to wait until there is a catastrophic incident before taking action.”
Publicly-funded tugs were deployed in the wake of the 1993 oil tanker disaster in which the Liberian-registered MV Braer ran aground in a hurricane, spilling its load off Shetland.
As a result of spending cuts, the four vessels serving the UK five years ago – two of which were based in Scotland – have been whittled down to just one.
In March, David Cameron questioned whether the remaining tug represented value for money.
The prime minister said the service, which costs up to £3million a year, was “currently used very sparingly”.
A senior UK government source later insisted the vessel would not be taken out of service until a long-term solution was found.
Maritime Minister Mr Goodwill has confirmed a “final decision” will be made before the end of September.
He added: “Maritime safety is always our priority and we have a range of measures in place to protect seafarers and the coastal environment, including 24/7 response from HM Coastguard.”