Nathan Kirsh, a little-known 76-year-old South African businessman, has increased his stake in listed London developer Minerva to 29%.

Kirsh, whose Kirsh Group of companies is based in Swaziland, an independent country within South Africa, increased his holding in Minerva yesterday from 27.2% to 29% through his Kifin vehicle.

He bought his initial stake in Minerva last May and then increased it to 20.4% in November, when he paid £3.4m for Aberdeen Asset Management's 15.47% stake.

Although the stakebuilding looks like it might lead to a takeover bid, Minerva’s shares have hardly responded to Kirsh’s interest. Today they stood at 14.25p, which values Minerva at £22.5m.

Kirsh's interests in Swaziland range from farm chemicals to milling and property through Swazi Plaza Properties, Swazi Plaza Towers and Mbabane Development Corporation.

Minerva has three projects under construction, two office buildings in the City of London - the Walbrook and St Botolphs - and the Lancaster Gate residential scheme overlooking Hyde Park.

It is also in discussions with investors over a joint venture for the Park Place shopping centre development in Croydon.