SYDNEY, June 4 - Two Australians and a New Zealander were wounded in a deadly attack by militants in London on Saturday, and a third Australian was also affected, authorities and media in both countries said.

At least seven people were killed after attackers rammed a van into pedestrians on London Bridge and stabbed revellers in nearby bars, the third militant attack in the country in as many months.

Islamic State claimed responsibility, the group's agency, Amaq, said on Sunday.

An Australian woman is recovering in hospital and another man received stitches and is returning to Australia, Foreign Minister Julie Bishop told Australian Broadcasting Corporation radio on Monday.

"We're still making enquiries in respect to the circumstances of the third Australian," she said.

The New Zealand High Commission in London is providing assistance to Oliver Dowling, New Zealand's Ministry of Foreign Affairs and Trade told Reuters in an emailed statement. Dowling was stabbed in the face, neck and stomach in the attack, New Zealand newspapers reported, citing Facebook posts from Dowling's family.

Australian media named two of the wounded victims as Candice Hedge and Andrew Morrison, and Sky News broadcast footage of Morrison holding a bloodied bandage to his neck.

"All of a sudden a guy comes up with a knife, I ducked it, but he got me," he said in the footage.

"I push him off, blood's going everywhere, I walk into a pub and I'm like: 'Someone help me, I've just been stabbed.'"

Police shot dead the attackers. At least 48 people were injured in the attacks, including French and Canadian nationals.

British Prime Minister Theresa May said Britain had to be tougher in stamping out Islamist extremism, declaring: "It is time to say enough is enough".

"The British prime minister is expressing the views and the opinions of the British people. They have been subjected to a number of brutal attacks," Bishop told ABC.

Less than two weeks ago, a suicide bomber killed 22 children and adults at a concert by U.S. singer Ariana Grande in Manchester in northern England, an attack Bishop described as "particularly horrible savagery".