The suspects -- K P Noohu, Ooma Babu and Shamsudheen -- are accused in the Coimbatore bomb blasts of February 14, 1998.
The Mumbai police sent a team to Kerala last week to probe Noohu's antecedents.
Noohu, who the police believe may have had a role in the Mumbai blasts, hails from northern Kerala's Kozhikode town (formerly Calicut). He is currently absconding. Noohu's associates -- Ooma Babu and Shamsudheen -- also hail from Kozhikode.
While Babu is currently lodged in the Coimbatore jail, Shamsudheen, who left Kerala 12 years ago, was recently arrested by the Coimbatore police for conspiring to blast buildings in the town.
"As in the 2003 Mumbai blasts, the latest blasts in Mumbai have some Kerala links. We have got some leads and we are investigating how many people were involved. We are in touch with the Mumbai police on this," a senior Kerala police officer told rediff.com
He said the Kerala police are trying to verify if those behind the 1998 Coimbatore blasts are connected with the Mumbai blasts. "That is a vital link we are probing," the officer pointed out.
After the 2003 blasts in Mumbai, a Mumbai police team travelled to Kerala to look for aeronautical engineer C A M Basheer.
Basheer, a former president of the outlawed Students Islamic Movement of India, hails from Aluva in Kerala. The police say Basheer, who wanted SIMI activists to be trained by Pakistan's Inter Services Intelligence agency, now operates from Dubai or Saudi Arabia.
While the police have ruled out Basheer's involvement in the current blasts, they believe Noohu was aware of the crime. Police sources claim Noohu knew Dr Tanvir Ansari, whom the Mumbai police have arrested in connection with the blasts.
Officials point to the Coimbatore blasts as the reason why Kerala attracts the Mumbai police's attention whenever there is a blast in that city. Most of those arrested in connection with the February 14, 1998 blasts in the Tamil Nadu town hailed from Kerala. Many ISI agents arrested from Karnataka and Tamil Nadu had Kerala connections.
The serial blasts that rocked Coimbatore in 1998 left 60 people dead and hundreds injured.
Police officers reveal a number of young men from the Muslim areas of north Kerala, especially the Malappuram district, are SIMI activists. Some of them may have been trained by militant outfits, the police say.
Several Islamic fundamentalist forces are active in Kerala, including the banned Islamic Sevak Sangh, the National Democratic Front, the People's Democratic Party, Jamaat-e-Islami, SIMI and the Darjgah-Jehad-O-Shehadat.
Two years ago, a report by the Union home ministry concluded that many ISI-aided groups in Tamil Nadu operate from Kerala.