Election Commissioner Somchai Srisuthiyakorn said the EC was calling in government officials involved in Ms Yingluck’s trips to the northern and northeastern provinces as it has allegedly received complaints of government resources being abused.
Mr Somchai said parties concerned had to carefully consider any exploitation of government resources during the issuance of a royal decree on elections.
The putting up of posters in support of a certain party at the end of such a trip could indicate government resources were being exploited and this could affect the election, he said.
The commissioner also noted the royal decree on the Feb 2 election remains in effect.
Mr Somchai said the EC has sought details of Ms Yingluck's upcountry visits from government officials on three occasions, but the officials failed to respond.
The EC will summon the officials to give information, he said.
Ms Yingluck yesterday visited a One-Tambon-One Product (Otop) complex in tambon Phu Khae sub-district of Chalerm Prakiat district in Saraburi.
Ten protesters showed up on two pickups and through loudspeakers accused Ms Yingluck of having a role in recent attacks at anti-government demonstration venues in Bangkok and Trat.
Local authorities protected Ms Yingluck from the protesters.
Pol Col Phubal Thapjan, deputy chief of Saraburi police, said a company of police officers was guarding the caretaker prime minister while other officers asked demonstrators to continue their protests peacefully.
He said police already knew who the protesters were.
Meanwhile, AM Monthol Satchukorn, an Air Force spokesman, said Ms Yingluck will attend a meeting of the Defence Council at the Royal Thai Air Force headquarters in Don Muang district, Bangkok, at 2pm on Tuesday.
If demonstrators show up, air force officers will prohibit them from entering the headquarters because it is a secure compound.
AM Monthol said air force chief ACM Prajin Jantong had ordered his subordinates to monitor the situation closely.