Two senior lawmakers from Singapore’s ruling People’s Action Party (PAP), have resigned over their “inappropriate relationship”, Prime Minister Lee Hsien Loong said on Monday.

The lawmakers, Speaker of Parliament Tan Chuan-Jin and Cheng Li Hui, have both admitted to the relationship.

While Chuan-Jin said that he had “fallen short” of the standards expected of him as a public figure, and that he was stepping down to “help heal (his) family”, Li Hui on the other hand has not made any public statements about her resignation.

The resignations is coming at a time of political turmoil in Singapore. Last week, transport minister S Iswaran and hotel tycoon Ong Beng Seng were arrested by the city-state’s powerful Corrupt Practices Investigation Bureau in a rare probe into high-level corruption. They have since been released on bail.

Already, political pundits have said that the resignations of Tan and Cheng are a further blow to the PAP, which has been in power in Singapore since 1959. The party has been facing increasing scrutiny in recent years, amid concerns about its dominance of the political landscape.

In a statement, Lee said that he accepted the resignations of Tan and Cheng with “regret”. He said that the party had “high standards” for its members, and that the two lawmakers had “failed to uphold those standards”.

A political analyst and associate professor of law at the Singapore Management University, Eugene Tan described the situation thus:”Taken together, I would say that this is the most severe political crisis to hit the ruling party since 1986 when the minister for national development was investigated for corruption.

“I think public trust and confidence in the ruling party would be significantly affected. And that puts the ruling party very much on the defensive,” Tan said.