Two unexploded M79 grenades were found near the house of anti-government People's Democratic Reform Committee (PDRC) leader Suthep Thaugsuban in Bangkok's Thawi Watthana district on Monday.
The incident follows the arrest of two soldiers carrying a large amount of ammunition near the PDRC's Lumpini rally site on Sunday night and came as the government asked the charter court to order an end to 'unlawful' demonstrations.
Pol Lt Col Chamnong Wongkunannya, an officer from Thammasala police station, said villagers living in Soi Phutthamonthon Sai 2 found the first grenade on open ground about 30m from the concrete wall of Mr Suthep's house.
Shortly afterwards the second M79 grenade head was found on an earth embankment about 30m from the location of the first device.
The two M79 rounds had apparently been fired from a spot nearby but did not explode.
Explosive ordnance disposal police were dispatched to examine the scene.
Villagers said they believed the M79 grenades were fired from an elevated bridge about 400m away.
Explosive ordnance disposal police destroy one of the two grenades found near protest leader Suthep Thaugsuban's house on Monday, March 10, 2014. (Photos by Chanat Katanyu)
In a separate incident, two soldiers were arrested in possession of two guns and a large amount of ammunition at a police security checkpoint near the PDRC's Lumpini rally site on Sunday night.
The arrest was made after police from Metropolitan Police Division 5 stopped a black Ford Ranger pickup truck registered in Bangkok for a search at about 11.30pm.
Travelling in the vehicle were Sgt Pitsanu Fueangrung and L/Cpl Nathawut Cherdsoongnoen, both attached to 31st Company of the 2nd Battalion of the Lop Buri-based Special Warfare Command.
Police searched the vehicle and reported finding one M16 rifle, 1,976 rounds of M16 ammunition, one custom model .45 Kimber pistol with seven rounds of ammunition, a pocket knife, two tear gas canisters, a set of brass knuckles and a backpack.
On being questioned the two soldiers refused to give a statement, saying that they would wait for officers from the Judge Advocate General's Department to arrive.
The two were initially charged with illegally carrying weapons and ammunition without permission and in violation of the emergency decree.
Maj Gen Warah Boonysith, commander of the 1st Infantry Division, said the two must first be questioned by police according to due process.
He said it was still not clear whether the the soldiers were acting on their own or had been hired.
Maj Gen Warah said the weapons seized did not belong to the unit the two soldiers were assigned to.
Meanwhile, the Centre for Maintaining Peace and Order (CMPO) has filed a petition asking the Constitution Court to order the PDRC to end its protests, which started in October last year.
Pol Maj Yuthana Praedam, a CMPO official, filed the petition on Monday on behalf of centre director Chalerm Yubamrung.
The petition states that the PDRC's protests have not been peaceful and without weapons, as required by Section 63 of the constitution. It also alleges that the anti-government group have carried out activities aimed at toppling the democratic administration and at capturing power through unconstitutional means in violation of Section 68 of the charter.
CMPO chief Chalerm said the decision on whether the emergency decree will be lifted and replaced with the lower-level Internal Security Act (ISA) rests with caretaker Prime Minister Yingluck Shinawatra.
The emergency decree, imposed in Bangkok, Nonthaburi and parts of Pathum Thani and Samut Prakan provinces, is due to expire on March 23.
If the decree were lifted and replaced by the ISA, the CMPO would likely fall under the supervision of the Justice Ministry and the police, caretaker Labour Minister Chalerm said.
He said emergency law is now ineffective, since the Civil Court has banned the CMPO from enforcing its orders.
He said he believed political turmoil could rumble on, adding that there would be problems if independent organisations such as the National Anti-Corruption Commission (NACC) and the Constitution Court were seen by some people as unjust. He alluded to the fact that the agencies have been accused of supporting anti-government protesters.
If the Pheu Thai Party stands firm on its legitimacy to govern and the PDRC persists in demanding that the government depart a "make-or-break situation is likely to follow", Mr Chalerm said.
Surapong Tovichakchaikul, caretaker Foreign Minister and chief adviser to the CMPO, said that the emergency decree should remain in place because war weapons were still being used to create violence.