The government decided to increase security for the two top leaders of the main opposition PML-N after the interior ministry carried out a review and came to the conclusion that there were serious threats to their lives.

In a letter written to the Sharif brothers on Thursday, Interior Secretary Kamal Shah told them that there were serious threats to their lives, Dawn News channel reported.

The two leaders will now be provided VVIP-level security, he said in the letter. VVIP-level security is currently provided to President Asif Ali Zardari [Images] and Prime Minister Yousuf Raza Gilani [Images].

In his letter, Shah also asked the Sharif brothers to remain alert wherever they go during the long march launched on Thursday by the lawyers' movement because of the threats.

Shah also asked them to cooperate with the officials deputed for their security. The move came after PML-N chief Nawaz Sharif said in a media interview that he fears assassination "from high-ranking government officials."