Rapidly expanding Cyprus-based shipowner Castor Maritime has raised another $18m to fund future purchases after buying 21 ships for $300m since July.

The Nasdaq-listed company said the senior term loan was secured by two of its tankers.

Castor has already drawn down the cash and said it would be used for general corporate purposes, including supporting growth plans.

The $18m financing matures over four years and bears interest at Libor plus 3.2%.

The company has never revealed how big it intends the fleet to get, but has signalled it has "significant" cash available.

Castor has previously raised most of its funds through stock issues, including a $125m sale of securities to unnamed institutional investors early in April.

New York's Maxim Group acted as sole placement agent for this offering.

Kamsarmax is the latest addition

Earlier in May, Castor acquired a 2013-built kamsarmax bulker for a price of $21m.

Brokers said the ship was the 82,000-dwt Peak Proteus, owned by Bermuda-registered Defender Holding.

The fleet now stands at 24 bulkers and tankers, an area it diversified into this year.

The Peak Proteus was added just days after the shipowner spent $49.5m on a South Korean-built fleet of five product tankers.

TradeWinds reported these vessels were sold by Greek owner Eletson Corp, which has been in protracted discussions with bondholders over a resolution of its debt.

The vessels going to Castor are the 106,000-dwt Megalonissos and Alonissos (both built 2004), the sistership Agathonissos (built 2002), and the 37,600-dwt Sikinos and Skyros (both built 2006).

Castor's eight-ship tanker fleet comprises one aframax, five aframaxes and LR2s, and two MR1s.