ISLAMABAD: Speaker National Assembly Ayaz Sadiq said on Friday that he is deeply aggrieved over the use of unparliamentary words, in an apparent reference to Pakistan Tehreek-e-Insaf Chairman Imran Khan cursing the parliament for allowing a ?criminal? to become the president of a party.

The NA speaker was addressing media in Islamabad, where he said that the lawmakers took oath for the dignity and protection of the parliament.

Sadiq said that if something was said in the house, he would have protected the august house but the matter took place outside it.

The NA speaker added that it was the aim of the lawmakers to protect the repute of the parliament and derogatory words are equal to destroying the institution. 

Earlier on Thursday, Minister of Railways Saad Rafique said that the ones abusing the elected parliament should apologise to the nation.

"Those cursing have lost the strength of argument," the minister said in a tweet this evening.

Rafique lambasted that the so-called honest individuals, who received salaries for being absent from the parliament, have stooped down to hurling abuses.

In a joint opposition protest rally to seek justice for the Model Town tragedy in Lahore on Jan 17, Imran Khan lambasted the parliament for allowing a 'criminal' to be elected as a party president.

"I send lanath (curse) the parliament that made a criminal the president of a party," he said, in an apparent reference to Pakistan Muslim League - Nawaz's (PML-N) decision to elect ousted prime minister Nawaz Sharif as its president.

PTI threatens to resign from National Assembly

Imran expressed 'complete agreement' with Sheikh Rashid's decision to resign from the lower house of the parliament. The latter had also urged the PTI chief to join him and resign from the National Assembly.

"I will consult my party over it, and it is very likely that we may join you [Sheikh Rashid]," he said, adding that resignations of his party were not accepted when they were submitted for the first time.