The NIST Speaker Recognition Evaluation (SRE) 2018 challenge comprises an open evaluation of the text independent speaker verification task. This paper summarizes the LEAP speaker verification systems submitted to the NIST SRE 2018. For all the speaker verification approaches, the front-end feature extraction involved the use of neural embeddings from a time delay neural network (TDNN) trained on a speaker discrimination task. These features, called x-vectors, are used in multiple ways for speaker verification task. In the first approach, the x-vectors with pre-processing and dimensionality reduction, are used with probabilistic linear discriminant analysis (PLDA) scoring. The second approach applies a speaker diarization scheme on the test segments containing multiple talkers before speaker verification scoring based on PLDA. The third system uses a local pairwise LDA model for pre-processing the x-vectors which are then scored using a Gaussian back-end. With experiments on the SRE 2018 database, we show that most of the systems achieved noticeable improvements over the NIST baseline in terms of the primary cost metric. Using a system fusion of the various approaches, we obtain significant improvements over the NIST official baseline (average relative improvements of 19.7% and 20.1% for the development and evaluation set respectively).