Allied London is preparing to start on site in spring 2008 with the next speculative office building at Spinningfields in central Manchester.
Mike Ingall, chief executive of Allied London, said: "We are hopeful that 3 Hardman Street will be 60% to 70% let by next April or May and we will then be in a position to start the next phase."
Ingall said the building to follow would be either 1 Hardman Street, fronting Deansgate, or 3 to 4 Hardman Boulevard, opposite the Royal Bank of Scotland's back office building. Each option would contain 150,000 sq ft of offices.
So far only Barclaycard has signed at 3 Hardman Street, taking 80,000 sq ft of the 350,000 sq ft. The credit card provider withdrew from its pre-let in March but is obliged to fit out the space.
Several banks and professional services firms have been strongly linked to 3 Hardman Street including law firm Pinsent Masons (30,000 sq ft), accountant PricewaterhouseCoopers (80,000 sq ft), Regus (30,000 sq ft) and Allied Irish Bank (25,000 sq ft).
Ingall declined to confirm the speculation but said talks were ongoing with several parties. He added: "It's the best office building in Manchester today and we are confident that with the quality on offer it will attract the leading firms looking for space in the city."
Quoting rents are £28.50/sq ft. Letting agents are Jones Lang LaSalle and DTZ.
Meanwhile, Allied is seeking a development partner for the 300,000 sq ft Manchester House site on the edge of Spinningfields, which will feature a 250-bedroom hotel and 150 flats. Ken Shuttleworth's Make architects is drawing up plans for a tower of up to 40 storeys ahead of a development brief reaching the market. Allied plans to sell a 250-year leasehold and retain the freehold.