Tension gripped Jammu city and Chenani town in Udhampur district in Jammu and Kashmir on Thursday following rumours about cow slaughter.Scores of Hindus blocked the Jammu-Srinagar highway at Chenani, 80 km from Jammu, after rumours gripped the town that a Muslim had killed a cow in the area.The district magistrate and senior superintendent of police of Udhampur rushed to the spot."There is no truth in these rumours and we have appealed to people to maintain peace and harmony," a senior police officer in Udhampur told IANS.Authorities increased security in areas of Jammu city where Hindus and Muslims live.With no official ready to go on record, informed sources said Internet services on mobile phones had been suspended in Jammu to prevent anti-social elements from stoking communal passions.