Senate President ProTempore Panfilo Lacson resigned as chairman of the Blue Ribbon, one of the most influential panels in the Upper House on Monday.

The Big Story television news program said Senate President Tito Sotto received his resignation letter.

Sotto said in news conference earlier in the day that Lacson was ''frustrated'' in his stint as head of the committee, which is investigating the flood control projects scandal.

''Senator Lacson is frustrated. He is not stressed. He is used to stress...But he will hold hearings and someone will ask why hold hearings. If he does not hold hearings, someone will complain,'' said Sotto.

Sotto said his investigation of the flood control projects scandal was ''very good.''

Sotto said three or four senators who could assume the Blue Ribbon chairmanship.

Justice Secretary Jesus Crispin Remulla described Lacson, a former chief of the Philippine National Police, as ''one of best investigators'' in the country. DMS