"Legal action has already been initiated by the company against those responsible for what it believes to be a coordinated shorting attack and reports are also being made on this activity to the appropriate regulatory authorities," Quindell said in a statement.

Gotham City Research questioned Quindell's revenue model and profit quality in a report on its website on Tuesday, wiping off more than half of Quindell's market value.

Quindell, which provides services to the insurance and telecom industries, said short positions were taken in its shares prior to the report being published.

Quindell said it would issue a detailed response later on Friday.

Quindell shares rose 4 percent to 26.06 pence in early trade on the London Stock Exchange on Friday.

(Reporting by Noor Zainab Hussain in Bangalore; Editing by Gopakumar Warrier)