LOME, Sept 6 (Reuters) - Togos opposition chief called on Wednesday for the immediate resignation of President Faure Gnassingbe, the current head of a half century-old political dynasty, rejecting a government move to introduce term limits as protests gained momentum.

Tens of thousands of protesters clad in red, orange and pink - the colors of Togos opposition parties - marched through the streets of the capital Lome as security forces looked on, a Reuters witness said. Some carried banners bearing slogans including Free Togo and Faure resign.

Gnassingbe has ruled the West African nation since his father died in 2005 after 38 years in power. The late President Gnassingbe Eyadema passed a law in 1992 limiting the president to two terms in power, only to scrap it a decade later.

Togos cabinet on Tuesday adopted a draft bill to bring back the term limits, the government announced in a statement. But the decision did little to satisfy an increasingly rejuvenated opposition.

Speaking before a crowd of thousands of protesters in central Lome, Jean-Pierre Fabre, the head of the main ANC opposition party, said: We will march again tomorrow. Faure should talk to us about the conditions for his departure. The (draft) law on mandates comes too late.