The attack near Baghdad airport killed Qassem Soleimani, the commander of Iran's elite Quds Force, and Abu Mahdi al-Mohandes, the deputy head of Iraq's Muslim Shiite militia Hashd al-Shaabi, along with six other Iran-allied militiamen.
On Saturday, the bodies of those killed in the strike were carried inside caskets onto military vehicles in a funeral procession led by Iraqi militiamen holding the Iraqi flag and banners of militias backed by Iran.
Iraq's caretaker prime minister, Adel Abdel-Mahdi, and Hadi al-Amiri, a senior leader in Hashd al-Shaabi, were in attendance.
Angry mourners chanted anti-US slogans such as "Death to America!" and called for revenge. Others raised placards reading: "We all are Soleimani and al-Mohandes."
Iraqi army helicopters flew overhead as part of tight security. Authorities had deployed hundreds of security personnel and closed main streets in the capital for the funeral, witnesses said.
The bodies are to be flown later Saturday to the holy Shiite provinces of Karbala and Najaf in southern Iraq for similar funeral processions, according to Iraqi media.
Afterwards, the slain Iraqi militiamen are to be buried in a major Shiite cemetery in Najaf, while the body of Soleimani will be flown to Iran for burial in his hometown, the reports said.
Soleimani was considered one of Iran's most influential military leaders, wielding influence in Iraq, Syria and other parts of the Middle East where Iran has a foothold.
Iran's Supreme Leader Ayatollah Ali Khamenei has threatened the US with "harsh retaliation" for his killing, while US President Donald Trump defended his decision to order the deadly strike by saying he had taken action "to stop a war."
Iraqi President Barhan Salih on Saturday called for regional and international cooperation to defuse tensions, state news agency INA said. He made his appeal during a phone conversation with Turkish President Recep Tayyip Erdogan.
"The Turkish president confirmed his interest in Iraq's stability, unity, sovereignty and independence and preventing Iraq from turning into an arena for regional and international conflicts," Salih's office said in a statement.
The United States nonetheless braced for retaliation, as Washington called on American citizens to depart Iraq "immediately."
On Saturday, Britain also warned its citizens against travel to Iraq or Iran.
Tensions between Washington and Tehran have escalated since Trump withdrew from the Iran nuclear deal in 2018 and reinstated US sanctions in what his administration calls a "maximum pressure campaign.
The Iraqi army on Saturday denied a report by Hashd al-Shaabi that an unidentified airstrike had targeted overnight a group of medics affiliated with the powerful militia in the area of Taji, north of Baghdad.
"The Joint Operations Command denies reports circulated by some media about such an air raid," the army said in a statement, carried by Iraq's official news agency.
The US-led military coalition fighting Islamic State militants in Iraq meanwhile said in a tweet it had not conducted airstrikes in Taji. - dpa/Asian News Network