About 200 international banks have signed a loan package agreement worth the equivalent of $8.7 billion, clearing the way for a $750-million stock offering to raise funds for constructing a tunnel under the English Channel. An official of the Eurotunnel Consortium said there were no plans to postpone the Nov. 16 stock offering, despite the battered state of global markets. But the stock offering could be delayed a few days if market conditions deteriorate further, he said. The simultaneous stock offering is worth $525 million each in England and France. In addition, $262 million was to be placed privately with overseas investors. The offer price of the Eurotunnel shares is expected to be 3.50 pounds each. The 31-mile rail link between England and France is scheduled to open in 1993.