A US company has called on the English High Court to block the controversial £3.9bn ($6.8bn) takeover of shipping giant P&O by Dubai Ports World (DPW).
The takeover of P&O has come up against stiff resistance in the US
Eller & Co claims that the takeover could cost it $150m ($86m) and affect up to 1,500 jobs at the port in Miami.
P&O's lawyers said the firm's legal challenge was "woefully thin".
The move came as US politicians also tried to block the purchase of P&O because of security concerns, and port workers protested.
Republican and Democrat politicians argue that the US would be more vulnerable to terrorism after the takeover, which would hand control of 21 US ports to a firm from the United Arab Emirates.
Speaking on Monday, New Jersey Senator Robert Menendez said that opposing the takeover was "about making sure we keep America safe".
"We're here to stand for a very simple proposition; our ports should not be in the operational hands of a foreign government," he said.
"What we don't want unloaded here is a chemical, biological or nuclear weapon."
In an effort to soothe the situation, DPW has agreed to a 45-day review of the security implications.
"We consider our company to be a friend of the United States," Michael Moore, a company executive told BBC Five Live.
The White House said on Monday that it welcomed the review.
DPW, which has said it plans to push ahead with the purchase, said it was surprised by the turmoil its bid had caused.
KEY US PORTS OWNED BY P&O
New York, New Jersey, Baltimore, New Orleans, Miami, Philadelphia
Buying P&O would turn DPW into the world's third largest port operator.
However, critics are pushing ahead with their attempts to stop the sale of P&O.
New Jersey officials are taking legal action to try and block the deal, while the Port Authority of New York and New Jersey is seeking to annul P&O's 30-year operating licence, claiming it failed to seek permission for the transfer of ownership.
Meanwhile in London, Eller, which provides stevedoring services at the port of Miami, has been arguing that the deal could be revoked in the US and that it breaches contractual agreements it has with P&O.
"There is a real prospect that the arrangement will lead to US port authorities revoking licences and leases held by joint venture companies which will cause sever financial losses," its petition states.