Pakistan has accused India of using artillery fire along the Line of Control with the intention of escalating tension between the two countries, PTI reported on Sunday. In a letter to outgoing United Nations Secretary-General Ban Ki-moon, Pakistani Ambassador Maleeha Lodhi said the alleged use of artillery weapons was the first such instance in 13 years.

Lodhi said the cross-border firing was a “clear indication” of Delhi’s intentions to “undermine regional peace and security”. Ceasefire violations by India had increased in the last two months, the ambassador said, adding that firing had led to the deaths of 26 civilians.

“Pakistan has condemned these continued ceasefire violations which are contravention of the 2003 Ceasefire Understanding,” the letter said, according to Geo News. Lodhi called on the UN Security Council to take note of the alleged ceasefire violations. The letter was later distributed as an official document of the Security Council.

Relations between India and Pakistan have worsened since the the crisis in Kashmir following the killing of Hizbul Mujahideen militant Burhan Wani. India has held that there has been an increase in ceasefire violations after it carried out surgical strikes on “terror launchpads”. The strikes by the Indian Army came after militants on September 18 attacked an Army installation in Uri, killing 19 soldiers. India had accused Pakistan of being involved in the attack, but Islamabad had dismissed the allegations as “baseless”.

Delhi and Islamabad have also been involved in a diplomatic row, with each accusing the other’s foreign officials of spying for their governments. On October 27, India had declared Pakistani High Commission official Mehmood Akhtar “persona non grata”. Eight Indian High Commission officials then left Pakistan following charges of indulging in “subversive activities”.