SEOUL - In a first public speech after a crushing defeat of his ruling party, South Korean President Lee Myung-bak vowed Monday he will shake up the cabinet and his office, Cheong Wa Dae.

The speech, designed to lay out his post-election policy priorities, came days after the crushing defeat of his Grand National Party in local elections in June 2, widely seen as a mid- term referendum on Lee's conservative administration.

"I take seriously the public sentiment displayed through the elections. I will listen to the voice of change the people want," he added.

Local media said the planned reshuffle of senior presidential secretaries will come next month, and the cabinet shake-up before the parliamentary by-elections on July 28. Opposition parties and some in the governing party have long called for personnel shakeup in the administration, considered by critics as prone to ignoring opposing voices.

"It was just a perfunctory speech that left out detailed plans for the reform," a spokesman of the main opposition Democratic Party, Woo Sang-ho, said in a briefing following the presidential speech.