The U.N. envoy to Libya says it's time for the newly-formed unity government to work after the arrival of its chief in the capital, Tripoli.

Yet the unity government is still awaiting a crucial vote of confidence by the country's elected parliament, which is based in eastern Libya.

Martin Kobler told reporters in Cairo on Thursday that "it's one thing to have an agreement with words and another thing is to implement the agreement."

He was referring to the U.N.-brokered political agreement between the country's rival factions struck in Morocco last December.

Based on the agreement, a new unity government aimed at healing the country's divisions is to take power and rule from Tripoli. The head of the government, Fayez Serraj, arrived in Tripoli last month by sea.