Istanbul: Rail passengers using Turkey’s new tunnel under the Bosphorus had to walk part of their journey on Wednesday when an electricity failure briefly halted services, just a day after its grand opening.

The 13.6km undersea tunnel in Istanbul — the world’s first linking two continents — was inaugurated with great fanfare on Tuesday as the government’s “project of the century”.

But a power cut forced passengers to leave the train and walk on the tracks, a transport ministry official said, before the problem was fixed and services resumed within a few minutes.

“The system failed after too many people pushed on the emergency stop buttons yesterday. This is what generated a power cut,” said the official who did not wish to be named, adding that first-time passengers had apparently pressed the buttons “out of curiosity”.

“The failure occurred at 8.12am (0612 GMT) and lasted two minutes. Passengers had to walk for 10 minutes on the tracks to reach emergency exits,” the source told AFP.

“The act of walking in the tunnel tracks is in line with the safety protocol... The train was operating at its maximum capacity, with at least 1,400 passengers.”

The tunnel, the fulfilment of a sultan’s dream of 150 years ago, is part of a €3 billion (Dh15.17 billion) transport project in Turkey’s biggest city.

Prime Minister Recep Tayyip Erdogan, a former mayor of Istanbul, revived the tunnel plan in 2004 as one of his mega projects for the bustling city of 16 million people — which also include a third airport, a third bridge across the Bosphorus and a canal parallel to the international waterway to ease traffic.

But his ambitious urban plans were one cause of the massive anti-government protests that swept the country in June, with local residents complaining they were forcing people from their homes and destroying green space.

Transport is a major problem in Istanbul, and each day two million people cross the Bosphorus via two usually jammed bridges.

Turkish authorities announced on Tuesday that the sub-sea train journeys linking Istanbul’s Asian and European shores would be free for the first 15 days.

The new railway tunnel is not fully operational yet and construction is expected to continue for several more years.

Erdogan’s critics accuse him of bringing forward the inauguration of the Bosphorus tunnel in time for municipal elections in March 2014.