Iran's Foreign Ministry strongly condemned the US deadly airstrikes on Yemen's capital of Sanaa and Saada province, including a centre where African migrants were kept.

In a statement, Foreign Ministry spokesman Esmaeil Baghaei denounced Sunday's bombings, which killed at least 78 people, including 68 African migrants held at a detention centre in Saada, and wounded dozens of others.

Baghaei described the US military attacks against civilian targets, vital infrastructure and people's houses in different parts of Yemen as "war crimes," "which have killed hundreds of innocent people."

He criticised the United Nations and international human rights organisations for their "silence and indifference towards this flagrant law-breaking and the frequent violations of Yemen's sovereignty and territorial integrity."

Baghaei called on Islamic states to take effective actions to stop the killing of Yemen's Muslim people and stop the continuation of Israel's "genocide" in Gaza and the West Bank, Xinhua news agency reported.

Earlier on April 28, the Houthis, who control much of northern Yemen, said all the victims are illegal African migrants held in the detention centre in Saada, the capital city of the namesake Saada province, in northern Yemen.

According to the International Organisation for Migration (IOM), Yemen remains a transit country for thousands of migrants traveling between the Horn of Africa and Saudi Arabia despite years of civil war in the country.

Tensions between the Houthi group and the US military have sharply risen since Washington resumed airstrikes on Houthi positions in Yemen on March 15. The strikes were intended to deter the Houthis from targeting Israel and US ships in the Red and Arabian Seas.

However, the reported airstrikes came hours after US Central Command announced that its forces had hit more than 800 targets since US President Donald Trump ordered an intensification of the air campaign against the Houthis on March 15.

The attack was one of the deadliest so far in six weeks of intensified US airstrikes against the Houthis, an Iran-aligned group that controls northern Yemen. The group has struck shipping in the Red Sea in what it says is solidarity with the Palestinians.