It confirmed it was committed in principle to the South Bank scheme, as well as separate proposals for an overhaul of the Royal Shakespeare Company's theatre in Stratford-upon-Avon, and for a new music complex in Gateshead.
Phil Murphy, Arts Council director, stressed that the support depended on the projects coming up with "high-quality" proposals offering value to the taxpayer.
Mr Murphy denied reports that the three projects would effectively be shelved by the Arts Council because it had run out of lottery money to allocate before the millennium.
"All three of these projects were identified by the Arts Council's full council last November as exciting projects which could make a real difference to the landscape for the arts," he said "That still remains the case."
Mr Murphy said each of the projects "will need to meet a list of demanding criteria and represent good value for money for the taxpayer and lottery- player".
He stressed that, contrary to reports, the three schemes would not be affected by the council's decision earlier this year to put a pounds 55m ceiling on the amount of lottery proceeds it would pay out for capital projects between now and April 2000. The "big three" schemes had separate budgets earmarked for them.
"Although we do not expect the RSC to come up with plans in the very near future, there could be detailed proposals within months from both the Gateshead Music Centre and the South Bank, and we look forward to receiving them."
The South Bank project could count on a maximum grant of pounds 25m, whereas the Gateshead scheme could receive pounds 40m.