Labour MSP Alex Rowley and the SNP's Richard Lyle called for "something to be done" to ensure benefits from multibillion contracts to build offshore wind farms are seen in Scotland.
It comes after Burntisland Fabrications (BiFab) entered administration following the collapse of a £2 billion contract to build turbine jackets.
Officials addressing the Economy, Energy and Fair Work Committee told the pair that state aid rules prevent the Scottish Government from forcing companies to guarantee work or contracts for Scottish firms in the supply chain.
The current system requires bidders for offshore wind farm projects to detail the economic benefits that would come to Scotland, although no legally enforceable minimum is in place.
Mr Rowley said this system is "completely unacceptable", adding that jobs coming to Scotland as a result of the contracts would be "in the hands of those developers and our ability to beg them for the crumbs".
He asked: "Should we not be bringing forward a moratorium on all these developments until we can actually sort that out?"
Crown Estate Scotland is in control of the leasing of seabed in Scottish waters for offshore wind farm.
Simon Hodge, its chief executive, said: "We have worked hard to create a context and an opportunity for developers to make a commitment to the Scottish supply chain, to demonstrate how they can work in collaboration, including through the Scottish Offshore Wind Energy Council, to achieve those ambitions of the offshore wind sector deal to play their part in helping to develop a successful supply chain in Scotland."
In relation to Mr Rowley's call for a moratorium, Mr Hodge said: "The bidding process is live at the moment and developers are actively working up their bids.
"The bid process is not yet concluded and until that process is concluded then theoretically the process could be halted but there may well be legal challenge and that level of challenge would increase as we move through the stages of the leasing process."
Mr Hodge confirmed the amount of work given to the supply chain cannot be a "material consideration" when bids are being assessed.
Mr Lyle said Scotland is being "let down" and "ripped off" by "state aid technicalities".
"Most people feel we've been getting ripped off for far too long and I along with Alex Rowley agree that something has to be done," he said.
"What are we going to do about it? Are we going to take on board what Mr Rowley is saying? I for one agree with him."
Mr Hodge said a requirement of business could lead to companies not offering bids at all, to which the SNP MSP said: "If they decide to go elsewhere, then we won't give them the contract.
"It's time to make sure that the Scottish workforce get a piece of the cake, not just a crumb, at least 50% of the cake."
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