Togo's new President Faure Gnassingbe has been sworn in despite international protests at his appointment.
Faure Gnassingbe vowed to "preserve the integrity of the nation"
Parliamentary deputies changed the constitution to allow Mr Faure to complete his father's term, after Gnassingbe Eyadema died on Saturday.
Togo's army was criticised for what the African Union called a "military coup".
The chairman of the West African community, Mamadou Tandja, told the BBC the events brought "shame to Africa".
Nigerian President Olusegun Obasanjo, who heads the African Union (AU), said the absence of a democratic transition in Togo was a threat to peace.
The US, UN, EU and former ruler France have also called for respect for the constitution. Western diplomats in Lome boycotted the ceremony.
"The United States urges all Togolese to respect strictly the constitutional process of Togo, which will lead to elections for a new president," the State Department said in a statement.
Mr Gnassingbe, 39, took his oath of office in front of judges and MPs at the presidential palace in the capital, Lome.
"I vow to preserve the integrity of the nation and to always be a faithful and loyal servant of the people," he said.
A BBC correspondent in Lome said a group of students was prevented from protesting at the ceremony and broken up by the police. Demonstrations have been banned for two months.
Mr Faure was chosen by the military late on Saturday.
On Sunday, deputies dismissed the parliament's speaker, who, under the constitution, should have assumed power after President Eyadema's death.
MPs also passed a change to the constitution so that there is now no legal requirement to hold elections in Togo within 60 days of a leader's death.
The new article states that the president of the national assembly succeeds the president and can stay in office until the end of the previous president's mandate. Mr Faure was unanimously voted head of the national assembly.
President Eyadema was elected for a five-year term in June 2003, which means his son can now rule until June 2008.
World figures have denounced Togo's army for its role in the transition of power.
France put its troops in West African countries on alert while the EU warned ties with Togo could suffer.
The exiled Togo opposition leader, Gilchrist Olympio, has called for a presidential election to be held at the same time as a general election due this year.
Togo's communications minister defended the army's actions.
Gnassingbe Eyadema rose to power in a military coup
Pitang Tchalla said the military had installed the new president and closed the borders to avoid a power vacuum. The borders have now reopened.
Eyadema, 69, Africa's longest-serving ruler, died while being evacuated for medical treatment abroad - reportedly from a heart attack.
After seizing power 38 years ago, he dissolved all political parties and governed unchallenged for more than two decades.
He legalised political parties in 1991, as a result of popular pressure, and won three elections.
But accusations of political repression and electoral fraud continued.