LONDON, Feb 21 (Reuters) - Morses Club's shares fell by as much as 67% on Monday after a profit warning and the abrupt departure of its chief executive, who the British sub-prime lender said in a stock exchange filing had sold stock without giving it advance warning.

Morses Club said in a trading update that a surge in customer complaints against its doorstep-lending unit "in recent days" meant that profit would be 20-30% lower than analyst expectations.

It also said CEO Paul Smith had left with immediate effect and its Chief Operating Officer Gary Marshall would take over.

Reuters was not immediately able to contact Smith through LinkedIn messaging or through Morses Club itself.

In a separate statement to the London Stock Exchange, where the company is listed on the AIM market, Morses Club said that it had received no prior notification of Smith selling shares which were worth about 200,000 pounds ($272,700) on Feb. 17, adding that it was notified of the sale the following day.

Smith sold 464,119 shares at a price of 42.65 pence each, the statement said.

Morses Club, whose shares closed down 63% on Monday at 14.825 pence, declined further comment on the share dealings.

A spokesperson for markets regulator the Financial Conduct Authority said: "As a result of our normal market surveillance, we are aware of these issues. In line with normal policy, we are not able to comment at this stage."

Analysts said the surge in claims against Morses Club was cause for concern given other subprime lenders had struggled to survive a spike in complaints.

Rival Amigo is battling in the courts after a deluge of mis-selling claims.

($1 = 0.7334 pounds) (Reporting by Iain Withers in London, additional reporting by Sachin Ravikumar in Bengaluru; Editing by David Goodman, Alexander Smith and Jan Harvey)