"I am deeply saddened because what is happening is not democracy; this is thuggery," President Bingu wa Mutharika said as he visited his new office on Capital Hill, the seat of government in Lilongwe.
"I appeal to the opposition coalition leaders, especially Mr (Gwanda) Chakuamba, not to encourage this."
Chakuamba accused the Malawi Electoral Commission of colluding with the ruling United Democratic Front to rig last week's election and proclaimed himself the rightful winner. His seven-party Mgwirizano coalition appealed on Tuesday to the High Court to order a rerun of the presidential poll, which international observers said was marred by serious irregularities.
The announcement on Sunday of Wa Mutharika's victory with 35% of the vote prompted two days of rioting in the economic capital, Blantyre.
Wa Mutharika said yesterday he was ready to work with all parties to help develop Malawi. Sapa-AFP