Thailand’s government has tightened regulations for the entry of foreigners, after two new imported coronavirus cases with possible exposure to the public raised concern about a second wave of infections.

Thailand has been 50 days without confirmed local transmission of the coronavirus, but two cases among foreigners this week has led to the self-isolation of more than 400 people and fears on social media of a new contagion.

The government acknowledged that regulations for diplomats and air crewmen, who were among a few categories of foreigners allowed to enter since March with self-isolation requirements, have been too lax.

“This should not happened, I am really sorry that it did and I want to apologise to the public,” Reuters quoted Prime Minister Prayuth Chan-ocha as saying.