West Bengal Chief Minister Mamata Banerjee has given a seven-day ultimatum to Maoists to lay down arms. She said negotiations for peace will continue but Maoists have to shun violence.Mamata Banerjee began her two-day Jangal Mahal visit last evening. She is in Maoist-hit West Midnapur District to monitor progress of development work with four District Administration of Jangal Mahal.Banerjee had earlier told our correspondent Arijit Chakraborty that lasting peace and development in the areas is the main objective of her visit to Jangal Mahal for the second time within three months after coming to power.