Mr Yatsenyuk is an ally of the jailed ex-PM Yulia Tymoshenko.

The offer came after talks on Saturday with opposition leaders in a new effort to end the worsening unrest that has spread across the country.

The interior minister had earlier said efforts to resolve the crisis peacefully were "futile".

Protests have gripped Ukraine since the government rejected a far-reaching accord with the EU in favour of stronger ties with Russia in November.

The crisis escalated this week when two activists were killed, and another was found dead with torture marks in a forest near the capital.

A 45-year-old protester is said to have died in a Kiev hospital on Saturday, after sustaining injuries in earlier violence.

Mr Yatsenyuk, parliamentary leader of the country's second biggest party, Fatherland, has not commented on the president's offer.

My Yanukovych has also offered the post of deputy prime minister to the former boxer, Vitali Klitschko, who is leader of the Udar (Punch) movement.

Ukrainian media also report that Mr Yanukovych has said he is ready to amend the constitution to reduce the president's powers.

The opposition has previously demanded that Mr Yanukovych step down.

Earlier, Ukraine's interior minister said talks with protesters had failed.

Vitaliy Zakharchenko - in charge of the police and one of the figures most despised by the protesters - blamed "radical groups" for the unrest, adding that protesters had arms.

"We will consider those who remain on the Maidan [the square] and in captured buildings to be extremist groups," he said

"The events of recent days in the Ukrainian capital showed that our attempts to peacefully resolve the conflict without resorting to forceful opposition remain futile," he added.

Although the protest movement - the "EuroMaidan" - is largely peaceful, a hardcore of radicals have been fighting pitched battles with police away from the main protest on Independence Square.

Mr Zakharchenko accused opposition of no longer able to control "radical forces" and of putting civilians in danger.

He also said that activists had shot a police officer and kidnapped three others - allegations denied as "false and dangerous" by protest leaders.

Later on Saturday, Mr Zakharchenko said protesters had released two officers, who were subsequently sent to hospital. Again, protesters called his words a provocation.

On Friday protesters seized a number of government buildings in Ukrainian cities outside Kiev, particularly in the west, which has traditionally favoured closer ties with Europe, including in the cities of Chernivtsi, Ivano-Frankivsk, Lutsk and Lviv.

On Saturday the protests spread to cities further east, including Vinnytsya, just west of Kiev.