The brutal assault this week on two opposition lawmakers outside the National Assembly could mark a resurgence of violence and overt oppression from the ruling Cambodian People’s Party, as it reverts to “old politics” in efforts to ensure victory in the 2018 election, according to observers.

Cambodia National Rescue Party parliamentarians Nhay Chamroeun and Kong Sakphea were beaten on Monday morning during a demonstration against the party’s deputy leader, Kem Sokha.

The CPP has denied any involvement in organising the protest – which was attended by its members and publicly anticipated by Prime Minister Hun Sen just hours earlier – but few are convinced.

“The protest was planned by the ruling party,” said analyst and founder of the Future Forum think tank Ou Virak. “It [the violence] was not a spontaneous thing.”

Rather than an isolated incident, Virak said he feared the attacks could be part of a wider CPP strategy to ensure a heavy-handed victory in the upcoming local and national elections in 2017 and 2018.

“The election season has come too early. Hun Sen is too eager to play politics – it’s a combination of eagerness and paranoia,” he said. “This is just the tip of the iceberg. I fear we will see a lot more of this on a bigger scale.”

He added that the protest emphasised the different strategies adopted by the premier to deal with his two opponents – Sokha and CNRP president Sam Rainsy – ahead of the elections.

While using violence and intimidation against Sokha, Hun Sen has threatened legal action against Rainsy over charges of forgery and incitement in hope that he will “flee the charges” ahead of the polls, he said.

Sebastian Strangio, author of Hun Sen’s Cambodia, agreed that Monday’s violence was likely “linked in some way to the elections in 2018 and increasing insecurity the ruling party feels about . . . continuing its hold on government.”

The violence, he added, “harks back to the previous era of Cambodian politics, something that was supposed to have ended”.

“This is old school Cambodian politics in an era of social media and smartphones.”

Following the attacks, Rainsy issued a statement criticising the CPP’s “fascist methods” and anticipating “more acts of political violence” in the coming days.

The opposition leader did not respond to questions yesterday about how the attacks and his blunt rebuttal would affect the all-but-dead culture of dialogue between the two parties.

But Chak Sopheap, executive director of the Cambodian Center for Human Rights, said the dialogue could not be maintained “when both parties resume old politics”. “Both parties should be focusing on messages that are positive and peaceful rather than war . . . [this is] old politics of intimidation and personal attacks.”

Paul Chambers, director of research at Thailand’s Institute of South East Asian Affairs, said Monday’s events showed Hun Sen had clearly abandoned efforts to negotiate with the CNRP in favour of time-tested tactics.

“When Hun Sen is unable to use the carrot, he will opt for the stick. That is what this is.”