Police officers across the country have been placed on alert amid security concerns following the military government's decision to strip Thaksin Shinawatra of his Thai passports.
Authorities are concerned that supporters of the exiled former prime minister might be planning actions in response to the decision.
The order from national police chief Pol Gen Somyot Pumpunmuang directed officers to monitor supporters of the former prime minister by working closely with local leaders.
Security measures at key tourist attractions, public transport depots, politically significant locations and residences of important persons must be stiffened as they could be targets, said the order circulated to all units on Friday, a copy of which was seen by the Bangkok Post.
Roadside checks will be carried out on main and secondary roads in Bangkok and vicinity, with the Arintharat special operation forces on standby if needed, it added.
Pol Gen Somyot ordered all metropolitan, provincial and district police station commanders to be ready in their areas of responsibility, and not to travel abroad.
The order did not mention Thaksin by name and said "ill-intended persons" could attempt to rally or stir trouble after the Foreign Ministry revoked the passports of "some persons holding political positions".
The ministry this week voided two passports issued to Thaksin by then-foreign minister Surapong Tovichakchaikul in 2011 shortly after he was appointed by Thaksin's sister, former premier Yingluck Shinawatra.
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Thaksin, who was overthrown by a coup in September 2006, fled Thailand shortly before a court sentenced him to two years in jail for corruption in 2008. He is based in Dubai but travels frequently in Asia and Europe.
He has said in the past that he carries a passport from Montenegro, and he is also believed to hold a passport from Nicaragua.
Thaksin is also facing the loss of his police colonel rank in connection with an interview in Seoul on May 20 in which he accused privy councillors of masterminding the coup last year.
Maj Gen Sansern Kaewkamnerd, the deputy government spokesman, reiterated on Saturday that the government had no political agenda to corner Thaksin. The actions against the former premier were being conducted in accordance with the legal process, he added.
Worachai Hema, a former MP for Samut Prakan and a leader of the red-shirt United Front for Democracy against Dictatorship (UDD), said the fresh attempts to neutralise Thaksin would prolong conflicts and ran counter to the reconciliation plan promoted by the government.
Cherdchai Tantisirin, another former MP and red-shirt figure in Khon Kaen, urged the government to look beyond Thaksin and deal with the broader issue of reconciliation.