Ukraine's President Petro Poroshenko has approved a law that will make it easier to impose economic sanctions on companies and individuals, according to Interfax news agency.

The law is expected to target companies and individuals in Russia that have been accused of assisting the pro-Russian militants in eastern Ukraine.

Ukraine's parliament had already agreed on the law in August, while the government has drawn up a list of people and companies that it wants to target.

Among those being lined up for sanctions is Russia's state-controlled gas giant Gazprom.

Ukraine has become embroiled in a price dispute with the company after it hiked the price it charges Kiev for gas after Russia annexed the Black Sea peninsula of Crimea in March.

Following months of negotiations, Gazprom halted gas deliveries to Ukraine in June.