The agency found that 43 out of 145 samples of lamb takeaway meals contained meat other than lamb in a review of local authority sampling data, from July to December 2013.
A separate investigation by Which? found that 40% of lamb takeaways had been contaminated with other meats.
25 of the samples tested by the FSA contained only beef, other meat species included chicken and turkey but no samples contained horse meat.
FSA said additional work will be done with local authorities testing 300 samples from takeaway restaurants and reporting their findings to the FSA from the beginning of May.
Andrew Rhodes, chief operating officer at the FSA, said substitution of lamb for cheaper meats in takeaway food is unacceptable.
“Prosecutions have taken place against business owners for mislabelling lamb dishes, but the recurring nature of the problem shows there needs to be a renewed effort to tackle this problem. Clearly the message isn’t getting through to some businesses.
“The further priority testing we have announced today will focus the efforts of enforcement officers and raise awareness amongst food businesses of the action they face for defrauding consumers.”
Almost half of lamb takeaways tested were found to be contaminated with other meats with some containing no lamb, according to Which?
The consumer watchdog tested 60 takeaway lamb curries and minced kebabs from restaurants in Birmingham and London and found that 24 had been mixed with meats such as beef and chicken.
Nick Martin, SVP at Trace One, traceability and product recall specialists, said: "It’s a real shame that these restaurants have been found to be deceiving their customers, and this latest scandal will no doubt leave a long lasting impact on the food industry.
"Retailers have been striving to change public perception and restore consumer trust in food products following the recent scares such as the horsemeat crisis, but news like this will have a much wider effect on the industry as a whole.”
The group seven of the samples contained no lamb at all.
The meat in five of the samples could not be identified, with the most likely explanation being it had been overcooked or re-cooked.
Food fraud priority
Richard Lloyd, Which? executive director, said the research uncovers evidence of food fraud more than a year after the horsemeat scandal.
“The government, local authorities and the FSA need to make tackling food fraud a priority and take tougher action to crack down on the offenders. This is vital to restoring trust in the industry, which is not only good for consumers but good for businesses too.”
In Birmingham, 16 of the 30 samples contained other meat and five contained no lamb.
Eight of the 30 samples in London were mixed with other meat and two of the minced lamb kebabs contained just beef.
Professor Chris Elliott, director of the institute for global food security, said the results came as no great surprise.
“Whenever issues about food contamination and adulteration are looked for in a serious way they are found. Without rigorous monitoring programmes in place cheats will always try to take advantage of consumers.”