Prime Minister Malcolm Turnbull says Australians are in solidarity with the people of Belgium following attacks causing multiple fatalities at Brussels airport and a metro station.

The attacks have killed at least 34 people and severely injured 200 more after two suicide bomb blasts at Zaventern Airport in Brussels, and a bombing at a Metro station.

Mr Turnbull confirmed on Wednesday morning (AEDT) that there were no reports of Australians being injured so far and condemned the “cowardly” attacks.

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“It is very early days,” Mr Turnbull told the ABC.

“But at this stage we are not aware of any Australians being involved. The ambassador has confirmed the embassy community is all safe and accounted for.”

“The Belgian people have our thoughts, our prayers and our resolute solidarity in this battle against terrorism.

The PM urged Australians from traveling to the region. Photo: AAP

“Indeed, Australia is allied with Belgium in this battle just as our forebears were 100 years ago in the fields of Flanders, in the First World War.”

Immigration and Border Force staff have cancelled all strike action until further notice after pressure by Mr Turnbull on Wednesday. The PM assured there will be adequate security at the airports in light of the terror attacks.

He vowed to do everything possible to protect Australia from a Brussels style attack, suggesting the country’ geographic location was favourable.

Foreign Minister Julie Bishop condemned the attacks and the Department of Foreign Affairs and Trade (DFAT) advised Australian travellers to reconsider their plans to travel to the region.

“We have upgraded our travel advice for Belgium to advise Australian travellers to reconsider their need to travel,” Ms Bishop said in a statement from Indonesia.

“Australians in Brussels should remain attentive to their surroundings, avoid affected areas and follow the instructions of local authorities.”

Victorian Premier Daniel Andrews said he spoke to Victoria Police Chief Commissioner Graham Ashton on Tuesday night and the state’s security level had been lifted.

Deeply concerned by the attacks in Brussels. Australians’ thoughts, prayers & solidarity are with the people of Belgium.

— Malcolm Turnbull (@TurnbullMalcolm) March 22, 2016

Leaders worldwide ‘outraged’

Leaders across Europe reacted with outrage, urging closer counter-terror co-operation on a continent that had been on high alert for months.

The 28 European Union (EU) leaders issued a rare joint statement saying they would combat terrorism “with all necessary means” after what they called “an attack on our open democratic society”.

Mr Obama said the US-led coalition will continue hitting IS militants. Photo: Getty

“The whole of Europe has been hit,” French President Francois Hollande said, whose country was still reeling from November’s terror attacks in Paris.

British Prime Minister David Cameron warned of the “very real” terrorist threat faced by countries across Europe, declaring: “We will never left these terrorists win.”

Mr Cameron’s spokeswoman said specialist police officers were being sent to Brussels to help with the investigation, as the Foreign Office warned against travel to Belgium’s capital.

“They will be gathering together as much material as possible that can help them with the investigation,” she said.

US President Barack Obama said the US-led coalition will continue hitting Islamic State (IS) militants.

“The thoughts and the prayers of the American people are with the people of Belgium,” Mr Obama said.

“This is yet another reminder that the world must unite. We must be together regardless of nationality or race or faith in fighting against the scourge of terrorism.”

The coalition is going to continue “pounding ISIL and we’re going to go after them”, he said.

Belgian King Philippe also condemned the “cowardly and odious” assault and said Belgium would “respond together with firmness, calmness and dignity”.

Any Australians who had concerns for the welfare of family and friends in the region should contact DFAT directly or if unable, to call DFAT’s 24-hour Consular Emergency Centre on 1300 555 135 or +61 2 6261 3305 if calling from overseas.

– with reporting by Kaitlin Thals and agencies