The White House press secretary, Sarah Sanders, has defended and elaborated upon Donald Trump’s description of undocumented gang members in the US as “animals”.

The president had referred on Wednesday to US members of the vicious El Salvador-based gang, MS-13, during an immigration meeting in Washington. But the comment was made during a bigger discussion with California elected and law enforcement officials, and was taken in some quarters as a broader smear suggesting that undocumented migrants pose a violent threat.

Sign up to receive the top US stories every morning

Speaking at the White House press briefing on Thursday afternoon, Sanders said: “I don’t think the term the president used is strong enough.” She added: “Frankly I think the term animal doesn’t go far enough and I think the president should continue to use his platform and everything he can do under the law to stop these types of horrible, horrible, disgusting people.”

At the meeting about sanctuary cities on Wednesday, Trump said of members of the gang: “You wouldn’t believe how bad these people are. These aren’t people. These are animals. And we’re taking them out of the country at a level and at a rate that’s never happened before.”

Trump has long made the gang, based in El Salvador, a target of his rhetoric. He visited Long Island to talk about the gang in 2017 and even explicitly mentioned the group in his 2018 State of the Union speech.

However, Trump’s comments sparked controversy. Catherine Cortez Masto, a Democratic senator from Nevada, tweeted “@realDonaldTrump, would you speak that way about your ancestors? Let me tell you something: When you attack immigrants, you’re attacking me. You’re attacking my grandfather who crossed the Rio Grande to pursue the American Dream. RT to tell Pres. Trump you stand with immigrants!”

This was echoed by the Democratic congressman Eric Swalwell of California, who tweeted: “IF you are a decent person and were in a meeting where @realDonaldTrump called immigrants ‘animals,’ you will denounce him NOW. Otherwise, what makes you any different?”

However, Sanders seemed to welcome questions on the topic in the White House briefing room on Thursday. “If the media and liberals want to defend MS-13 they are more than welcome to,” said the spokeswoman. She noted that the organization is “one of the most vicious and deadly gangs that operates by the motto ‘rape, control, kill’.”

Shortly afterwards, Trump returned to the subject when questioned by reporters at another event at the White House.

He said: “I’m referring, and you know I’m referring, to the MS-13 gangs that are coming in … And if you look a little bit further on in the tape you’ll see that. So I’m actually surprised that you’re asking this question, ‘cause most people got it right.”

He went on to say: “MS-13 – these are animals … We need strong immigration laws. We have laws that are laughed at on immigration. So when the MS-13 comes in, when the other gang members come into our country, I refer to them as animals and, guess what? I always will.”