Europe Combined Terminals is going south to protect its business in the north.

Europe's biggest container handling company is close to signing a contract to run a ''box'' terminal in the Italian Adriatic port of Trieste and is mulling a move into the Spanish port of Bilbao.ECT also plans to create a network of inland terminals deep inside Europe to upgrade services to its customers. The first will be built at Duisburg on the river Rhine, the world's biggest inland port, and more hubs are planned for Central and Eastern Europe.

ECT has stayed in the black in a notoriously low-margin business - it booked pretax profit of 40 million guilders ($20 million) on revenue of 643 million guilders in 1997. But margins are being squeezed as the big shipping lines demand improved performance and lower rates - something public port authorities can promise but private firms can't easily deliver without straining their finances.

The move into the Mediterranean is aimed at protecting ECT's core business at its two Rotterdam deep-sea terminals - 3.95 million 20-foot containers last year.

New Mediterranean transshipment hubs such as Malta and Gioia Tauro, able to handle the giant containerships plying the Europe-Asia trade, pose a threat to the Le Havre-Hamburg range of ports, the traditional point of entry to the continent.

''It's a fact of life, and the best response is to be part of the new opportunities,'' said Jos Dekkers, ECT's director of communications.

ECT is also facing intense competition in northern Europe as rivals take aim at Rotterdam's 42 percent share of all the containers passing through the Le Havre-Hamburg range.

The pressure increased last week, as Antwerp decided to build a $400 million, 2.5 million-containers-a-year terminal, and BLG, the main stevedore in Bremen/Bremerhaven, and Eurokai, the second largest operator in Hamburg, unveiled plans for a partnership leading eventually to a merger.

ECT lost out in the bidding for the previous terminal concession in Antwerp and is unlikely to enter the fray again. ''Antwerp isn't high on our list,'' Mr. Dekkers said in an interview.

ECT will focus first on the Mediterranean, particularly on ports with which it lacks feeder links. It saw off competition from Sinport, a subsidiary of Italian auto giant Fiat, and Clarke Chapman, a unit of Britain's Rolls Royce, to win a 30 year lease on Trieste's Molo V11 terminal. Immediate plans are to boost its current yearly throughput from 200,000 to 500,000 20-foot containers by 2000.

Success in Trieste will compensate for the failure of ECT's first move abroad - a stake in a container terminal in the Latvian port of Riga, which it quit last year.

While ECT will concentrate on ports in the Mediterranean - it is carrying out a feasibility study in Bilbao - it will probably look beyond Europe later, according to Mr. Dekkers.

The decision to build a 100,000-container-a-year terminal in Duisburg, deep in Germany's industrial heartland, reflects ECT's determination to keep pace with its customers' demands.

Shippers wanting to pick up or deliver containers will be able to choose between Rotterdam, an ECT rail terminal at Venlo on the Dutch/German border, and Duisburg. ECT plans to operate a daily barge service between Duisburg and its Rotterdam terminals.

Other potential sites for inland terminals are the Czech republic and Hungary, Mr. Dekkers said.

While it expands abroad, ECT's biggest challenge is here in Rotterdam, where contract negotiations with one of its biggest customers, Denmark's Maersk Line, are dragging at a snail's pace.

ECT balked at the line's opening demand for a completely exclusive terminal such as the one it operates for U.S. carrier Sea-Land, and the two agreed last year to a joint venture.

ECT remains tight- lipped about the Maersk dossier. ''We are still talking,'' Mr. Dekkers said.

But ECT, as well as the other European container stevedores, knows the lines have plenty of options along Europe's coastline.

Maersk and Sea-Land, which are in an alliance, recently decided to switch the British port of call for their Europe-Asia service from Southampton to Port of Felixstowe.

And Evergreen, the Taiwanese carrier, is spending $50 million on a new hub in the Southern Italian port of Taranto, taking some of its 200,000-container-a-year business from Gioia Tauro.