MANILA, Philippines — Former Justice secretary and senator-elect Leila de Lima on Thursday said that she will be an opposition against the anti-human rights policies of presumptive President Rodrigo Duterte.

"When it comes to anti-human rights policies I will definitely be an opposition, oppositionist and a fiscalizer," De Lima said in a press conference after being proclaimed as senator-elect.

Duterte earlier said that he wants to restore the death penalty and to introduce execution by hanging as part of a law-and-order crackdown once he takes office on June 30.

READ: Tough fight looms over death penalty | Shoot-to-kill, hanging await criminals

De Lima, however, stressed that summary executions are illegal, inhumane and unconstitutional.

"Summary execution is murder. Summary execution is criminal," De Lima said.

The elected senator noted that investigation on the Duterte-linked Davao Death Squad (DDS) is ongoing before the Department of Justice (DOJ).

"We'll see," De Lima said when asked if she will push for a Senate probe on the DDS.

Last year, a word war erupted between De Lima and Duterte when the former condemned the latter for summary executions and the DDS.

This started when international group Human Rights Watch called for an investigation into the alleged links of Duterte to the death squad. Duterte then challenged the group to file a case against him.

Last month, the DOJ confirmed that the National Bureau of Investigation has been conducting a fact-finding probe on the DDS since last year.