A US Senate committee has inserted language into upcoming legislation that would block $77.8 million in aid to Cambodia unless the government ceases its “violence and harassment” against human rights workers and the political opposition.

The appropriations committee bill, sponsored by Republican Senator Lindsey Graham of South Carolina, said the fiscal year 2017 funding – which includes more than $33.6 million for health programs – would not be made available if they fail to receive certain assurances from the State Department.

“None of the funds appropriated by this Act may be made available for assistance for Cambodia unless the Secretary of State determines and reports to the appropriate congressional committees that the Government of Cambodia has ceased violence and harassment against civil society in Cambodia, including the political opposition,” the bill reads.

Four human rights workers and an electoral official have been behind bars for more than two months for their alleged roles in a purported affair involving Cambodian National Rescue Party acting president Kem Sokha, who himself has been holed up at party headquarters for more than a month to avoid arrest.

On Friday, the Ministry of Justice formally requested that the National Assembly lift the immunity of two lawmakers it seeks to charge over allegations related to “prostitution” for allegedly facilitating the trysts.

News of the potential withholding of US aid comes less than a week after Prime Minister Hun Sen lashed out at foreign donors he said were using aid as leverage in the ongoing political crisis, saying he could not be “easily pressured” and that “Cambodia dares to play [its cards] and is not afraid to lose”.

Beyond the current political situation, the US bill also stakes out fresh ground on the Khmer Rouge tribunal, saying that future funds will only be delivered on the condition that the court moves forward with controversial Case 003 against alleged former naval commander Meas Muth.

Prime Minister Hun Sen has consistently warned that moving forward with cases 003 and 004 could risk plunging the country into civil war.

Government spokesperson Phay Siphan yesterday said the prime minister would not be swayed by the US government’s threats or “bribery”.

“[It is] laughable that they use the money to bribe the rule of law … it is a form of corruption,” Siphan said. “We don’t want to see high-ranking people getting away from the rule of law … Human rights workers are not untouchable people like the mafia.

“We are against impunity. Why do they protect Kem Sokha and the other people through bribery? It is the NGOs who abuse the law.”

He added that while vulnerable Cambodians may be affected by aid cuts, the government “had no choice” but to remain firm in their stance; however, opposition spokesperson Yim Sovann urged the ruling party to heed the message from the US.

“That reaction and statement from the US is very clear – the ruling party should reconsider their political stance and the political situation right now,” Sovann said. “They must respect human rights; they must not oppress the opposition or human rights and environmental activists.

“We should sit down and talk and find a solution to end the political crisis.”

Regional analyst Carl Thayer said the statement could be the start of other sanctions, but they needed to be directly aimed at the prime minister if they were going to have any impact.

“Cambodia’s Achilles’ heel is that it needs access to the US for their garment industry … they can’t sell to China, obviously,” he said. Thayer added the US would pursue a human rights agenda even if it meant pushing Cambodia into the arms of China.

“[Hun Sen] will brazen it out. Some of this is going to be public posturing… but it’s also calculating … he knows he can’t get too isolated,” he said.

Human rights analyst Billy Tai pointed out that the bill, which is still in committee, could face multiple obstacles before becoming enshrined in law and that while it was a “strong statement”, it could amount to “an empty threat”.

“The government is quite smart at how they deal with and manipulate donors,” Tai said. Tai said by the time the bill took effect, the current batch of political prisoners would likely be released, only to be followed by a fresh cycle of political crises.

“The intimidation factor is incredible; the international donors almost seem to be ignoring that. The underlying issues are never really dealt with,” he said.