A Victorian MP who was barred from entering the US while on a parliamentary study trip has accused the Trump government of discrimination.

It comes as his Labor colleagues lashed out at the Trump administration over the "extraordinary and unprecedented" events which led to Muslim MP Khalil Eideh​ being denied entry to the US.

Speaking next to a baggage carousel at Melbourne Airport after a 48-hour journey home, a bleary-eyed Khalil Eideh​ also revealed on Saturday afternoon that he had dual Syrian-Australian citizenship. 

"I am exhausted, very very disappointed and frustrated," Mr Eideh said. 

The MP was blocked from boarding a flight from Vancouver to Denver this week while on a taxpayer-funded trip to study drug policy and injecting rooms.

His parliamentary colleagues had no issues boarding the flight.

"All my colleagues went through and I was blocked from entering the United States", he said. "I have been discriminated against .

It is not known whether the Lebanese-born MP fell foul of the Trump government's travel ban, which bars citizens of Sudan, Somalia, Iran, Yemen, Syria and Libya from travelling to the US.

While he described the Trump ban as "totally wrong" he said he did not think it was behind his rejection. 

"They couldn't find my name and when I gave them my itinerary they said unfortunately it is blocked and we can't let you on the plane and that was it."

Mr Eideh, who is the deputy president of Victoria's legislative council, said he was born in Lebanon, he had automatic Syrian citizenship through his parents.

He said he shared this information with authorities before they issued him with a US visa five weeks ago.  

He said he had relatives in Syria who he last visited at Christmas. When asked if he supported the Assad regime, Mr Eideh said his loyalties lay with Australia.

Mr Eideh was joined at the airport by Labor Senator Kim Carr, who lashed out at the US government's treatment of an ally. 

"Quite clearly, Khalil has been a victim of Trumpism," Mr Carr said.

"We are seeing the chaos that reigns in the US."

He said the incident was unprecedented and he was waiting for an explanation from the US government. 

"I find it an extraordinary proposition that a member of an Australian parliament with a valid visa, travelling on an official passport undertaking parliamentary work, can be stopped from entering the United States without explanation," he said
 

Shadow Minister for Foreign Affairs Penny Wong said Labor was "deeply concerned" that Mr Eideh had been denied entry to the US.

"Mr Eideh is an elected member of State Parliament and was travelling on a valid visa," she said.  

"Labor is seeking an explanation as to why Mr Eideh was denied entry by the US."

Foreign Affairs Minister Julie Bishop has asked Australian officials to make urgent enquiries. 

"Like Australia, the United States administers a strict entry regime and the decision on who can enter the country is a matter solely for the US government," a spokeswoman said.