"The party suffered heavy losses in West Bengal and Kerala which was quite unexpected," he told mediapersons in Thiruvananthapuram.
The failure to form the Third Front before the elections and certain parties' wavering stand towards the front had also contributed to Left poll debacle, he said.
"The setback suffered by the LDF (Left Democratic Front) cannot be seen as people's sentiments against the government. The party's Central and state leadership would examine the reasons that contributed to the defeat," he told mediapersons as the Congress-led United Democratic Front swept the polls, winning 16 out of the 20 seats in the state.
Asked whether he was hinting at the rival group in the CPI-M headed by state unit secretary Pinarayi Vijayan for the defeat as it worked out the poll strategy and spearheaded the campaign, the 86-year-old leader said all aspects of the verdict would be studied.
On the national scenario, he said the defeat of the "communal" National Democratic Alliance was a relief, but return of the Congress with its "anti-people economic policies" and "pro-American foreign policy" was not a desirable development.