Leaders of the National Unity Platform have strongly condemned the arrest of the party's spokesperson, Joel Ssenyonyi, and secretary general, David Lewis Rubongoya.
The two leaders were apprehended on Monday morning.
The reasons for their arrest remain unclear.
The NUP head offices in Kamwokya, Kampala, were placed under heavy police and military presence on Monday, ahead of the party's 'special prayer session' for the missing party members.
Mathias Mpuuga, the Leader of the Opposition in Parliament, stated that the military siege of the party headquarters and the arrest of the Secretary-General and the party Spokesman reflect a lack of democracy in the country.
"This occurring on a day when the country is supposedly celebrating its 61st Independence Day only goes to show that we are still under colonialism - only the colonisers' skin colour has changed," he said.
Dr Daniel Kawuma, the NUP Diaspora team leader, stated that this act of repression highlights the concerning lack of independence in Uganda, with political parties engaged in lawful activities being targeted and subjected to arbitrary arrests and imprisonment by the Museveni family.
On Uganda's 61st "independence" day, the police and military forces raided the NUP party headquarters, preventing the party leadership from addressing the nation.
Kawuma emphasised that this blatant abuse of power and infringement on the rights of Ugandans should not go unchallenged.
"We call upon the international community, especially the United States and other Western nations who finance the Museveni family regime, to demand accountability and cease enabling this culture of impunity.
The West must not stand idly by while a regime oppresses the Ugandan people without regard for their constitutional rights, individual liberties, and democratic principles," he said.
He demanded the immediate and unconditional release of Rubongoya, Ssenyonyi, and all other unlawfully detained NUP supporters by the Museveni regime.
"The National Resistance Movement (NRM) claimed to have liberated Ugandans in 1986, but their actions resemble those of our slave masters, abducting, torturing, and violating the rights of Ugandan citizens," he said.
He urged Ugandans and the international community to speak out against such blatant impunity.
"Silence is not an option when fundamental freedoms are trampled upon.
We must unite to defend democracy, uphold the rule of law, and protect the rights and dignity of every Ugandan," he said.
