A long-anticipated new metro line linking Cairo's Abbasiya and the northeastern suburb of Heliopolis -- the second phase of Cairo's third underground line -- was inaugurated on Wednesday morning in a ceremony attended by Egypt's interim President Adly Mansour.

The new phase, which was due for completion in 2013, contains four tunnel stations: Exhibition Grounds, Cairo Stadium, Kolleyet Al-Banat and Al-Ahram.

According to Transport Minister Ibrahim El-Demery, who was present at the inauguration along with Prime Minister Ibrahim Mahlab, the new route is 7.7 kilometres long and will be operated through seven air-conditioned and Egypt-manufactured trains.

It is expected to transport around 600,000 passengers daily along with the first phase, which links two of Cairo's busiest squares: Ataba, just south of Downtown Cairo, and Abbassiya, several kilometres to the northeast.

The phase is worth LE4.3 billion and will employ 124 workers from the Egyptian Co. for Metro Management & Operation.

In September 2012, Egypt’s government agreed 940 million euros worth of loans with the French Development Agency and the European Investment Bank to help fund an extension to Cairo's third metro line (the third phase).

The European Investment Bank (EIB) has, meanwhile, contributed 600 million euros to be repaid over 25 years within the same grace period.

When complete, Cairo's third metro line will stretch 43.5 kilometres from Cairo airport to Imbaba in Giza. The third phase of the line will be 18 kilometres long and include 15 stations, according to a transport ministry statement. A fourth line is due to be completed by 2019.

A sprawling metropolis with well over 16 million inhabitants, according to latest figures, Greater Cairo has for years wrestled with a growing traffic congestion problem.