Theresa May wonders if police have 'powers' they need to deal with terror

— -- U.K. Prime Minister Theresa May condemned a bombing that took place on a London Underground train this morning as "cowardly," telling ABC News chief anchor George Stephanopoulos it's time to examine whether Britain’s police have the full capabilities they need.

Friday's attack was the latest in a string of terror attacks in Britain this year.

"The police and the security services are doing the work necessary to discover the full circumstances of this cowardly attack that's taken place, and to identify all those who are responsible," May told Stephanopoulos in an exclusive interview that will air on "This Week" Sunday.

In a speech following a terror attack on London Bridge earlier this summer, May called for a change in counter-terrorism efforts, saying it's time for "some difficult, and often embarrassing, conversations."

Asked by Stephanopoulos about her comments, May replied, "It is necessary for us to look, as we are doing, at whether our police and security services have the full capabilities, the powers that they need. Of course we review after any incident that takes place, and we have had, sadly, a number of terrorist attacks in the U.K. this year."

In light of the attack, May said she plans to bring up terrorists' use of the internet to spread extremism when she's in the U.S. for the United Nations General Assembly next week.

"One of the issues that we really need to be addressing, and I'll be raising this -- when I'm at the United Nations, is the question of the use of the internet by terrorists," May said. "But also this using it for the spread of extremism, of hatred, of propaganda that can incite and can inspire terrorism."

May went on to criticize U.S. President Donald Trump for commenting on the London attack while the investigation was still active.

"I don't think it's helpful for anyone to speculate on what is an ongoing investigation," May told Stephanopoulos.

Trump took to Twitter to comment on the attack Friday morning, which left at least 29 people injured.

The country's threat level was raised to "critical" after Friday's attack.

May praised emergency services for responding quickly.

"I'm pleased to say that our emergency services were on the scene of this attack immediately," May said. "Once again, I admire and thank them for their professionalism and bravery."

See more from ABC News chief anchor George Stephanopoulos' interview with U.K. Prime Minister Theresa May on "This Week" Sunday.