Manila: A proposed treaty on increased rotation of American troops within Philippine bases nationwide, which is currently negotiated by the United States and the Philippines in Washington, might have unconstitutional provisions and could sour relations between China and the Philippines, said lawmakers who are against any such accord.

The treaty can “virtually make the Philippines a US colony,” complained Congressman Neri Colmenares of Nation First, a leftist sectoral party at the House of Representatives.

“It could deteriorate China-Philippine relations and divide the 10-member countries of the Association of Southeast Asian Nations (Asean),” said Congressman Jonathan de la Cruz, who also belongs to another sectoral party at the lower house of Congress.

Senator Miriam Santiago said the presidential palace should allow the Senate to review the agreement.

At the same time, Senate President Franklin Drilon, an ally of President Benigno Aquino, called for a briefing from the departments of foreign affairs and national defence to clarify the issue on Senate’s concurrence on the proposed treaty.

Right-wing lawmakers see the proposed expansion of US troops all over the Philippines is the best deterrent to China’s flexing of maritime muscle in the South China Sea, in view of the weakness of the Philippine Armed Forces and the intensification of tension due to overlapping claims in the South China Sea.

Spokesman Herminio Coloma said the proposed US-Philippines Enhanced Defence Cooperation does not need the Senate approval because it is an offshoot of the US-Philippines Mutual Defence Treaty (MDT) which was signed in 1958; and the Visiting Forces Agreement (VFA) which was ratified by Congress in 1998.

But critics also said that the proposed treaty is being fast-tracked ahead of the arrival of US President Barack Obama in Manila in April, following a tour of other Asian countries.

When the VFA was ratified in 1998, US military access began in 2000, but was limited to port visits and joint US-Philippines joint war games.

But in 2002, US Special Forces were deployed to extend intelligence assistance to Filipino soldiers who are fighting the Abu Sayyaf Group, Al Qaida-linked militants based in Mindanao, southern Philippines.

In 1991, the Philippine Senate rejected the US-proposed 10-year extension of the now defunct US-Philippine Military Bases Agreement (MBA), the basis of US presence in the Philippines since 1898, the end of Spanish colonial rule (that began in the 16th century).

Since 1992, with the ouster of US troops from two large US bases in Subic, Zambales and Angeles, Pampanga, the Philippine began the privatisations of these places.

The end of the Cold War continued with the dismemberment of the former United Soviet Socialist Republic (USSR) and the dismantling of two former USSR Bases in Cam Ranh Bay and Danang.

There are also US bases in South Korea and Japan.

The US has decided to strengthen its presence in the Asia Pacific as tension in the South China Sea has intensified. China, Taiwan, and Vietnam claim the whole of the sea-lane.

Brunei, Malaysia, and the Philippines claim some parts of the Spratly Archipelago off the South China Sea, based on the United Nations Convention on the law of the Sea (UNCLOS) that grants countries 200 nautical mile exclusive economic zone starting from their shores.