Morocco's capital Rabat is rebuilding its seafront and in so doing uncovering a vast treasure trove of relics, artefacts and ruins.

"We have made some fantastic discoveries not only for the history of Rabat but of the kingdom," said archaeologist and historian Mohammed Essemmar.

Essemmar, 43, heads the heritage department of the agency in charge of redeveloping the Bouregreg valley, a watercourse linking the twin cities of Rabat and Sale.

Roman columns and capitals, 12th-century enclosing walls, Islamic ceramics and coins have emerged from the sands.

The prize discovery in the 2,500 square-metre (27,000 square feet) site is the enclosing wall of the Tachfin "ribat,"or military camp, attached to the Oudayas casbah, dating from the 12th century and completed during the brief reign of Almoravid dynasty King Tachfin ben Ali (1143-1145).

The base of the wall was unearthed in late 2006, made up of the "ribat's" two corner towers and a central tower.

"The old texts mention its existence but we did not know here it was, because at the end of fierce battles the founder of the Almohad dynasty Abdelmoumen ben Ali (1130-1163) rased the camp to build the Oudayas casbah," said Essemmar.

"It is great, because outside Marrakesh Almoravid remains are very rare," said Essemmar, who hold degrees from both French and Moroccan universities.

But there have been other pleasant surprises. Archaeologists have uncovered a chamber that must have been used as an armoury and at the end of last year found an arched passage dating from the 17th century and linking the Street of the Consuls, a famous commercial street in the Medina, or old quarter, with the seafront.

The excavations, which have cost 110,000 euros (143,000 dollars) provided by the agency, have disrupted the plans for development work.

"For the first time developers and archaeologists are on the same wavelength: my town-planning and architect colleagues have changed their plans to reconstitute history," said Essemmar.

Work will begin next month to restore to the road the appearance it had at the start of the Alawite dynasty founded by Moulay Cherif (1631-1636), ancestor of the reigning monarch King Mohammed VI.

The plan to redevelop the Bouregreg estuary began in January 2006 and has six phases. It seeks to rehabilitate and transform the two banks into major tourist and urban centres.

Partner investors in the United Arab Emirates have contributed to the 2.75 billion dollar cost of the two first tranches of the work.

In July Essemmar was woken by a pre-dawn phone call from workmen who had found in a creek three large marble Roman columns with their capitals.

"The river has in its belly hundreds of treasures and when we drag it we shall make some terrific discoveries, because with its 2,500 years of history it is a real archaeological museum, " said Essammar.

In any case, said the agency's information officer Omar Benslimane, efficiency has to go hand in hand with heritage.

"It is a building site which we have to complete, but we are certain to come across other ruins: we shall then suspend the work to call up archaeological expertise.

"We shall carry out rescue excavations. If we find that it is something important we shall change our plans. One thing is certain, nothing will be ignored as in the past."